Shoal draft / centerboard

[Meerkat]

Interested in thoughts on these for a blue water boat. I know Hinkley did one or more designs using this feature (the one I recall had a 5' "shoal" draft and a 9' c/b down draft).

I really like the idea of the changable draft and keeping the c/b housed in the shoal keel (out of the cabin, plus no leaks inside), but wonder about maintenance and etc.

[Frank E. Price]

The 34' Chinooks (built by Cascade in Portland) have such a setup. Friends in Ketchikan of years ago owned one (maybe still do) and it was a sweet-sailing boat. But the centerboard had been removed and the slot plugged by a previous owner. The little I've heard about centerboards that aren't accessible afloat hasn't been good. If the board gets jammed from grounding out, you have to lift the boat out to get at it. But based on my limited experience sailing a Chinook I would say that if you're not competitive shallow draft is a good thing -- forget the board in a largish boat.

Frank

[Hwyl]

Most Ted Hood centreboard designs are like that. There are plenty of others out there. S&S did some the list goes on and on.

[Meerkat]

I don't doubt that they exist, but more about their practicality for people not equipped with a triple-platinum credit card in case something goes awry! I recall the Hinkley I once read about used a hydraulic system to raise and lower the board. While I'm not thinking of anything remotely as grandiose, considerations such as board jamming or something caught in the trunk are of interest/concern.

Maybe I should ask about this as a broader issue: just how much of a role does draught play in going to weather? I would like to get close inshore, but have no interest in being able to go aground.

What about reaching - how much draught do you need then?

(mutters incantations towards John Hardiman)

[Frank E. Price]

Well, you'll go aground whether you're interested in being able to do so or not, so best be able to without screwing things up.

How much draft means how much lateral resistance doesn't it? That's an awfully open-ended question and I couldn't answer it anyway with anything but opinion, but it'll sure be interesting to see what Hardiman has to say about it.

How about a leeboard(s)?

Frank

[Meerkat]

My Sea Pearl 21 had leeboards. They worked more or less well enough, although they sometimes "swam" out away from the hull (maybe I was on the wrong tack or something). At least they where small enough that they didn't make the boat look like a duck or a swan or something, like some boats with huge leeboards.

Bilgeboards might be an option, although they might leak inside at the pivot?

[Hwyl]

Centreboards are well worth the aggravation. On a very upmarket 55' S&S I used to run there was a piece of rope attached to the top of the centreboard, it came up through a tube to deck level and then to a simmle winch. (A wedge shaped peice of the board stuck out. I defence of Ted Hood, yes he does or did design million dollar boats, he started small just like every one else and he enjoyed small boats. Every time I met him he was a down to earth, one of the boys kind of guy. Let's not knock success. I'm in awe of the fact that he has a stay named after him (Tedstay, it's a temporary stay to pull against spinnaker pole compression) that puts him up there with Mr Cunningham and Mr Highfield.

The best centerboard system that I've seen is on a Dyer Dhow. There is a sqare section hole through the board, the shaft has a corresponding square section and round sections of different sizes where it goes through the case sides and a permanently attached lever. Sorry I can't draw it, but they work, with rubber washers to stop leaks.

[Meerkat]

Oh, believe me, I'm not knocking Ted! I thought one of those Hinkleys would have made a fine home, where it in my price bracket! The intent was more to underscore that rich boys can afford much more expensive toys then most of us.

I think I read about this Hinkley (could it have been a So'wester?) in the mid 60's in ?Yachting? at a base library while living in Germany. I was 15 at the time and anything and everything about boats was way cool to me back then - still is! smile.gif

[Aramas]

I've put a lot of time and thought into researching and visualising centreboard arrangements, and I'm not entirely happy with the idea of a centreboard trunk entirely below the waterline. About the only way of accessing such an arrangement is on a hoist or cradle, or perhaps careened or dried out on it's side. Then there's diving of course smile.gif

If even part of the case is clear of the wl then it's possible to use a batten pushed down the side of the board to dispatch any accumulated gunk or pebbles that cause it to jam. If not, I believe SOL is the appropiate term. Still, the type of arrangement you're talking about still sails pretty well without the cb, so it comes down to losing a few degrees of pointing ability, and an engine can compensate for that until the boat mechanic gets paid.

Personally I like a boat that dries out upright smile.gif

[Tom Lathrop]

If you are really interested in a bluewater boat, why consider a centerboard at all?

On the other hand many people, including me, have had good experience with them in coastal water where the shallow draft comes in very handy and the deep draft with the CB down give windward performance much better than the shoal draft types. Unless you don't care about windward performance or tacking ability, fixed keel shoal draft boats make a big concession for skinny water ability.

Centerboard boats went out of style due to race rating penalties, not for practical reasons.

The Bristol 35.5 is a good example of a boat that can work well in coastal water. It is more tender than if it had a deep draft keel of the same ballast ratio. There are some maintenance issues but if they are taken care at every haulout for bottom painting, it is a reliable and worthwhile system.

Just about everything on a sailboat can break or give problems and a CB is no different.

[Bill Perkins]

I own a 23 ft. Ted Brewer designed yawl with such a setup .I think the best term for these boards that stay below the cabin sole is swing keel, just to avoid confusion .It works fine . Visualizing the board in the raised position ; there's a vertical fin at its' after end .This does poke up in the after end of the cabin in the form of a very short case with a plugged hole in the top , well above the waterline .Through this hole you can push with a rod , or hammer it down if you have to .

[Ian McColgin]

There are swing keels - more often on wee boats like the McGregors - where it's really a keel carrying much of the vessel's ballast.

There are centerboards, like Goblin's all oak board. Sometimes these must be ballasted a bit to get them down or, as in Goblin's (an Alden 43' schooner, they may have enough board in the trunk above the waterline that they stay down without lead.

And finally there are the complex things like the Hinkleys, essentially a bronze board so it at least contributes to the ballast and can be made to keep very low and have no trunk in the cabin.

Advantages and disadvantages:

A fully moving keel, whether swing or drop, gives the most ballast furthest down. It is very hard to lift and the trunk takes considerable engineering to survive a shock grounding or capsize. The more verticle daggerboard models also may bang as the boat hobbyhorses over waves.

A board like Goblin's is great if the hull has the stability anyway. The board only contributes to windard ability, not stability at all. It's lovely when taking the ground. At moderate speeds it's simply an early warning. At high speed it will bump and deflect, but then return to it's shape.

I've dealt with all metal boards after a hard grounding. Once bent, it's not going back in the trunk. On once such, bent in a pretty moderate grounding, we lay the boat on her side with the tide and tried to use the boat's own weight to lever the board back straight. Didn't work. In the end, we extracrted the board, made a huge fire on the beach, and once it was all nice and hot about a dozen of us pounded away with sledges till it was straight again. What a pain.

The bronze boards of hinkleys would be subject to such problems but hinkley sailors seem to be so careful that they don't run aground.

The complex hydrolics of some board systems are subject to impact damage in groundings or collisions.

The cable gear, such as Goblin had, could foul in the trunk if the board was too far down at the time of the grounding. The pendant should not be exposed below the trunk when the board is in the right place.

On Goblin's rig, it was possible to get the right coursensess of sand wedged in the trunk enough to prevent lowering after a dry-out. I kept a purposed made 'bad saw' to reef out between board and trunk by diving. I also built a metal pad at the top of the board near the pendant so I could take the cap off where the pendant pully was and lower an iron rod to pound a bit. In smaller boats like the dory Leeward and on my friends Wianno, we have a purpose made hole in the trunk for insertion of the #*%&stick. For the Wianno, I keep promicing go get a bit of fur and make a merkin for the hole . . .

Any trunk can either weakend the backbone of the boat or be an opportunity for an improved box structure, depending on how smart the designer is. Either way, the trunk slot can open a bit in a grounding, allowing sand in and weakening the boat a little. Most of the Alden 43's of Goblin's vintage were keeled over for this reason. Goblin had a full length cast iron keel with the slot in that, so there was no problem.

Pete Culler and others off set the CB trunk. This allows the keel to remain one piece and keeps the actual slot above the bottom when the boats dried out. It adds a touch of turbulence.

As with any boat considerations, anything works at least some time and nothing works all the time. It's all an integrated compromise.

[Hwyl]

[QUOTE]Originally posted by Tom Lathrop:
[QB]If you are really interested in a bluewater boat, why consider a centerboard at all? end of quote

Because they are much better in a blow, really we haven't discussed this, but if you are lying under bare poles or storm sails centreboarders (board up) don't get thrown around so much.

The other nice thing: if you have a long keel/ centreboard combination and have to manouver under engine power in tight situations, dropping just a small amount of board gives you something to pivot around, and decreases your turning circle enormously (I used to call it "the bow thruster")

Both these observations are from experience. I have my own pet theories as to why these work (it's more obvious in the bare poles situation)it's hard to believe that just a small amount of board would make turning easier but it does.

[ 12-28-2003, 09:40 AM: Message edited by: Hwyl ]

[Tom Lathrop]

Originally posted by Hwyl:
Because they are much better in a blow, really we haven't discussed this, but if you are lying under bare poles or storm sails centreboarders (board up) don't get thrown around so much.
[/QB]There was a Venture dealer in Atlanta that advocated this as a proper and better way to weather a storm. There is probably a wind and water condition range where this is true as the boat should slide sideways instead of laying over as a result of the lateral resistance of the down board or keel. Trouble is, if the storm is bad enough to generate breaking waves, you can get turned on the side or even turtled with not enough ballast to right the boat. A couple of deaths on Lake Lanier in the '80s were attributed to an overturned Venture which was found with the keel in the trunk and family inside.

When I attempted to counter the dealers advice to his faithful, I was accused of being a wimp by the dealer. He made no comments following the drownings.

Keel up may be more comfortable sometimes, but a down and locked keel is safer. Of course, this does not apply to keel centerboarders with the majority of ballast in the stub keel where I would raise the unballasted board in a storm.

[ 12-28-2003, 12:59 PM: Message edited by: Tom Lathrop ]

[Carlsboats]

My experience with centerboards -- I now have a S&S yawl with one, and previously had a Controversy 26 -- is that it is entirely practical to house the board beneath the cabin sole, below the waterline, but the boards do add cost and building complications. Are they worth it? For the Chesapeake Bay, where I ran aground at least once a year, having 4 feet of draft on a 40-footer made it all worthwhile. Now that I am in New England, if I were building the boat again, I would add draft and forget the centerboard.
On the S&S C.B.yawls (ther are lots of them. including Finisterre), the whole works is bronze -
centerboard, centerboard case, lift tube. Nothing leaks. The pivot pin is in the lead ballast. The lift pennant comes up through a tube and goes to the top of the cabin house, where it meets a big winch. The case is capped with a bronze plate that is bolted and gasketed in place. For service (yes,you have to lift the boat) the cap piece comes off. But the pennant can be replaced without hauling the boat, as it goes through a sheave in the top of the board, with both ends coming up into the boat, giving a 2:1 purchase. Also, the part of the pennant that is immersed is rope -- no wire to corrode.
We have had trouble with a bent board only once --as a result of Hurricane Bob in 1991, when the boat was thrown up on a beach. Then, we had lots of worse problems than a bent board. But to straighen the board, which is 3/4" bronze plate, and which bent about an inch in five feet, we laid the board on some blocks on the ground, and ran a forklift truck over it. If I was building the boat again, I think I would go with a much thicker board -- maybe 2" total -- built up out of fiberglass with a metal skeleton inside. metal.

[Lucky Luke]

Hi Meerkat,
And happy new year to all.

Since you ask for centerboard vs. shoal draft, there is a compromise (shoal draft) which receives more and more favors from yachtmen / architects: these are the twin bilge keels.

They proove very efficient as far as the boat's performance is concerned (just about as good as a deep fin), are great for tidal waters, aso...

BUT: they are most valid on "beamy ass" designs (I can explain in details, but will take long time), and their positionning, angles, eventually asymetrical profile are all quite tricky. No way to be attempted by someone who would not have enough datas to refer to, and it is worth confirming by tank testing; out of reach for the one-off amateur builder.

Still, it is very much worth considering it if you want to ask to an experienced NA to do the design.

[Meerkat]

Luc; I have read up on bilge keels and know that they can actually be better than a single keel, but also, as you say, they require a good bit of design engineering to accomplish their benefits fully.

This is one boat I've bee looking at. I really like the 2'/5' c/b up/down change in draft for one thing. I also like the trad gaff look too.

http://www.selway-fisher.com/PLouisd1.gif

This attractive pocket cruiser was designed for a client on the island of Mauritius and has some of the hull design features of the indigenous craft with their sweet and not over wide transoms married to traditional English work boat hull shapes with plumb stem and fairly hard bilges giving excellent stability and sea-keeping qualities. Construction is for strip planking over computer faired mould shapes. She has an inboard engine as well as a swing keel which does not intrude into the cabin space. The cockpit is large and the cabin is laid out generously for 2 crew. LOD (ex bow sprit) 20'3" (6.17m); Beam 8' (2.33m); Draft 2'/5' (0.61/1.55m); Approx. Displ. 3528 lbs (1600 kg); Ballast 992 lbs (450 kg); Sail Area 240 sq.ft (22,36 sq.m.). The strip plank technique gives me pause. I've read and been told that it's a lot of work and it's not the easiest to repair in remote parts of the world. I also would prefer a boat with wider side decks, but that's a build detail, not something cast in concrete.

[Aramas]

This thread seems to be confusing several things and using them interchangably.

Bilge Keels are unballasted fins on the bilge that are used to make a yacht dry out more or less upright and provide a little extra lateral area and roll damping. They're sometimes used on ships purely as roll dampers and there are also active variants.

Bilge Boards are unballasted retracting boards whose sole raison d'etre in cruising boats is to provide lateral area without being in the middle of the accommodation. The bilge-daggerboard variant is sometimes used in racers with only one deployed at a time and are angled so that they are more or less vertical when heeled.

Twin Keels are dual ballast keels. They're usually used to provide shallower draft and permit drying out on an even keel. Some of their proponents also attribute them with more comfortable motion and even with better performance than a single keel(?). They provide good roll damping, but as with any biplane arrangement they are less efficient than a single keel of the same total area and aspect ratio.

Centreboards are, well...centreboards! smile.gif

Swing Keels are ballasted centreboards.

Dagger Boards are of course centreboards that are poked through the bottom of the boat rather than pivoted.

Drop Keels are ballasted daggerboards.

Oh, and just in case you thought I'd forgotten to include some unsubstantiated opinion (perish the thought!), the only items on that list that I approve of are centreboards and bilge keels smile.gif

[ 01-01-2004, 11:22 AM: Message edited by: Aramas ]

[Ian McColgin]

I'm not fond of that kind of heavy swing keel without some serious modification.

It will bump if you get out in a really steep chop after the boat ramps up a wave at over 45 degrees and then hits the crest, and again at the trough if the bow rises really fast. This can be fixed if you have a strong port into which you can insert a preventing stick or, as some McGregors have, you make a pin lock that wors from the trunk.

The pendant is free of the trunk, placed aft no doubt to give better leverage. In a good grounding the pendant can foul between the trunk and the keel as the keel comes up into the boat. Sometimes the stiffness of the pendant - ss 7x7 cable - will do the trick but I'd not count on it.

Three solutions I've given different boats:

If there's room below the winch, a bit of solid rod from the keel up to just inside the trunk. If you can build in some limits on its fore and aft swing, then the rod will always keep the cable from flapping down and jamming. (This works best if there's a long tube taking the cable really high, like to the coachroof.)

Cover the pendant up to the trunk with some plastic hose. If the lower end is V notched to fit over the keel a bit and pinned in place it will keep the pendant from folding too much. Like the rod approach, the hose should end just inside the trunk and hopefully can wind up a turn or two on the winch.

Hardest to rig but nice if you can do it is a bungee cord from inside the top of the trunk about half way forward. A bit of tension and attached to the pendant by a ss ring so it can slide. When the pendant goes slack in a grounding, that will pull the pendant forward and keep it from making a bight that flaps outside the trunk.

Or perhaps a powerful coil spring on the winch that takes tension as you lower the keel, assists you with some of the load winding it up, and rapidly reels in the pendant in a grounding.

All ya gotta do is . . .

[Dave Hadfield]

Drake, my 40ft ketch, has a shallow 3/4 length keel, most of it cast iron for ballast, with a slot in it for a large-ish, traditional steel fan shaped CB. The hull has some deadrise. As a result she draws 3ft 4in board up. I find this quite convenient. It's great to enter a crowded anchorage (and anchorages are crowded more often than not) just before sunset and still find a place to swing on the hook.

A CB like this is easy to replace. I did it 2 years ago because the original was corroded. I got a welding outfit down the road to make it up out of 3/8 steel, had it galvanized, and now give it a coat of cold zinc every year. Pretty simple and cost not much.

It's easy to remove when on the hoist using its own winch at one end and a halyard led through the cabin skylight at the other. The pin must be a sloppy fit though. Mine is a 18/16" pin in a 20/16" hole. There is no kind of reason to make it tight.

The CB trunk forms the most lovely and large mahogany drop leaf-table you can imagine. It also allows inspection and/or pushing from above. I even mount a tin wood stove sometimes in a pan that fits ito the inspection slot.

It all works for me, and the shallow draft makes it far more practical for coastal waters.

You can of course, place CBs in different places, as in Bolger's St Valery, or Spaulding Dunbar's tandem arrangements.

Jim Michalak puts the CB outside the hull. At first glance it looks like a leeboard, but it's prevented from winging outwards, thus works on both tacks. On a smaller boat there's a lot to be said for this.

[Lucky Luke]

Originally posted by Aramas:
This thread seems to be confusing several things and using them interchangably.

Twin Keels are dual ballast keels. They're usually used to provide shallower draft and permit drying out on an even keel. Some of their proponents also attribute them with more comfortable motion and even with better performance than a single keel(?). They provide good roll damping, but as with any biplane arrangement they are less efficient than a single keel of the same total area and aspect ratio.

Oh, and just in case you thought I'd forgotten to include some unsubstantiated opinion (perish the thought!), the only items on that list that I approve of are centreboards and bilge keels smile.gif Bilge keels / Twin keels...oh sorry sorry my Lord smile.gif , you're right, please forgive your humble servant....
But may I say that your affirmation concerning the latter are wrong, and that referring to the aspect ratio is not appropriate ? tongue.gif

Like to discuss the subject? (in a very amicable way that is)?

[Aramas]

Sure:)

I was just trying to fit it into a one liner without thinking about it too much. They're not making any more brain real estate you know!

Leastwise not in my head anyway smile.gif

[Lucky Luke]

Originally posted by Aramas:
Sure:)

I was just trying to fit it into a one liner ....They're not making any more brain real estate ...
One liner???..brain real estate?? :confused: :eek:
I'll be dammned if I understand an ounce of that! And it's NOT in the Oxford dictionnary :(

Shiite, I have to accept the fact that I'm far away from being anything like an English speaker..or...just a suggestion: what about YOU my dear checking the dictionnary :D

[Dave Hadfield]

Luke, just odd expressions.

A one-liner is a joke that can be told in one sentence, a snappy remark.

Real Estate is property, land, usually referred to this way when it's for sale.

[Eric Sea Frog]

Good sum-up, Aramas. Tanks for sharing.
My ideas on the subject were rather hazy, I'm afraid!

[Meerkat]

For commentary on why twin keels can produce better performance than a monokeel, see;

http://www.kastenmarine.com/roll_attenuation.htm

and

http://boatbuilding.com/content/twinkeels/

The main advantages are as follows:

1. Higher sailing speeds than an ordinary cruising yacht of similar dimensions. Surprisingly, part of the reason for this is the relatively small wetted surface, which yields improved light air performance. Modern twin keels are of high aspect ratio and present less wetted area then a full keel or long fin keel while retaining the steady helm associated with full keels.

2. The twin keels become more effective with increased angle of heel, while a single keel becomes less effective. Because twin keels cant outward at the tip, the leeward keel becomes more vertical and deeper in the water as the boat heels. The windward keel is working more horizontally creating downward lift that increases righting moment giving more power to carry sail. Also with this cant outward from the vertical, leeway forces water up to the root of the fin as opposed to spilling over the tip in a single keel. Hydrodynamic tests have shown that decreasing end tip loss can double the effectiveness of a fin (the sole purpose of keel winglets).

3. The wave pattern reshapes to reduce the fore and aft crests. At hull speed a hollow forms amidship, but the bilge keels cause a wave to form in this hollow, canceling out the stern wave and giving a flatter wake. This increases the maximum speed of the hull, as much as 15 - 20%, in the same way that a bulbous bow or stern bustle works; by reducing wave making resistance at hull speed where it constitutes 85 - 90% of total resistance. To ensure the desired effect is at cruising speed the correct fore and aft placement of the keels and proper proportions must be checked by model testing. This placement is critical, as the model data shows. Too far forward or too far aft and the resistance will dramatically increase.

4. The deep plunging of an ordinary hull is avoided by the stabilizing action of the fins which are also very effective in dampening out rolling motions. The fins also provide a certain amount of lift to the stern at speed when the hull is upright. The effect of this lift is to flatten the trim angle, i.e. reducing squatting, which flattens out the wake and lowers the resistance.

5. Directional stability is markedly enhanced by the fins. This is demonstrated both by tank tests and full size yacht performance.

6. Speed and fuel consumption under power are better then usual. The prop can work in clear water without being shrouded by the keel and rudder. In the case of the motorsailer we were testing, 85 h.p. would produce 14 knots. Also the yacht can be controlled in reverse, which is seldom true of single keel yachts.

7. The rudder areas are smaller for the same reason as the keels. Each rudder is more effective as it works upright, deep in the water.

8. Both keels and rudders can be asymmetrical (more curve on one side than the other) like a wing, and tailored to work on their one specific tack. This again makes them more efficient allowing smaller appendages. Generally it is felt that both the rudders and keels can be made 25-30% smaller because of the greater efficiency.

9. Windward ability equal to that of an ordinary yacht is achieved on a fixed draft approximately comparable to that of a centerboarder without the problems associated with lifting foils. Windward performance in rough water is superior because of the roll and pitch dampening abilities of the keels.

10. Stability is equal to that of an ordinary yacht without recourse to extreme beam. Righting moment and range of stability are at least equal to those of a well designed centerboard yacht of relatively deep fixed draft, because ballast can be placed in each fin the ballast is as low as any keel-centerboarder.

11. The general advantages of twin keels include the ability to take groundings in a level position. This allows the bottom to be cleaned and painted (although the shorter and shorter keels are making this more precarious), without the cost and nuisance of a haul out, as well as being easily shipped without a cradle. When sailing in shallow water, if one should touch bottom, the boat rights and clears itself. This is possible because twin keels draw more water when heeled than upright, unlike single keel boats which when righted dig themselves in deeper.

[Stiletto]

Can you give an example of a design where the twin keeled version outperforms the fin keeled version, or must the design be specific to twin keels?

[Meerkat]

The remarks in the second URL, above, mention twin keel versions of monokeel designs that outperform the monokeeled versions, but does not mention specifics.

[Aramas]

I've seen those sites before, and the thing is, I don't believe them smile.gif

It's all very well to replace a poorly optimised fin keel with some very carefully (ie expensively) worked out twin keels and claim that, since they perform better than the existing fin, that twin keels are therefore 'better'.

The hydromechanics of biplane configurations are quite well understood, and their effects have been well documented since the 20's. Did anyone notice that there are not a lot of biplanes on the tarmac at the local airport? There's a reason for that. They suck smile.gif

The main reason for using a biplane configuration in the old days was that they were easier to brace. They're only used in aircraft these days to either provide shorter wingspan, or in the case of aerobatic aircraft, to provide a lot more aileron area and so react more quickly to control input.

[TR]

I know nothing about biplanes, but the above long list of claims concerning the effectiveness of twin keels is nothing but sales hype. The claims are all made based on some tank tests, what the author found in those tests just is not so IRL. Some of these claims are somewhat true, but always with a bunch of qualifications, which generally rule the twin keels not applicable.

There are other published and unpublished tank tests which show the exact opposite findings. There is a good reason why every cruising boat designed in the last 20 years is not equipped with twin keels. They are slow.

All the best, Tad

[RodB]

I cannot help but mention designs such as Alden, S&S, and atkin here.

I would be interested in any comments on the centerboard designs in the Alden boats in the 32-45 foot LOA range, especially the gaff rigged schooners. From the book on Alden's designs there are a few yachts that fell in the size range above with centerboards. I have never seen any of these and am very interested in the design of the centerboards in Alden yachts, perhaps some comments on their performance, and how they have stood up to use over time.
Just curious...??? Also Sparkman/Stephens' and Atkin's similar sized designs are of interest.
RB

[ 01-05-2004, 03:47 AM: Message edited by: RodB ]

[Andrew Craig-Bennett]

I think the name to conjure with, above all others, in keel/centerboarders, is

PHILIP RHODES

seaworthy, strong, fast, docile and incredibly good looking.

[rbgarr]

I agree.

Phil Rhodes Swiftsure class design: 32+' long, 3'6" draft with bronze centerboard retracted, roomy, reasonable sailer, attractive proportions. Another interesting Phil Rhodes design is the 28' Jingleshell 'turtleback' sloop.

[Ian McColgin]

Goblin was an Alden 43' schooner. She was wrecked beyond my repair in Hurricane Bob and a succession of dreamers have only enabled her to sink deeply into the midst of some honeysuckle.

She was just a hair different than the 43's built by Goody and Stevens. Made a few years later for a fellow who owned an iron foundry next to the boat yard.

When I visited the Alden office and purchased her plans, we laid them down over the regular plans and could see the differences, mostly a bit more hollow at the bow. We believed that with the longer mass of the iron keel, Alden felt that she's have a slower pitching moment.

The huge one piece iron keel is a marvel. The CB slot goes through it and thus the slot does not pant at all when she takes the earth. It's for this reason that Goblin retained her CB while the G&S boats, so far as I could learn, were all keeled over by the early 60's.

There's a remark about an early LFH schooner with the CB mounted under the elevated main step that he saw that as an engineering opportunity. But such geniuses aside, for real longevity with a CB, there's nothing like an iron keel to lend a bit of structure.

It did clang pretty hard if I hit a rock. For banging hard stuff, lead is more soothing.

Goblin's board was wood - massive oak thing - and enough of it was above water line when down that it only needed a little lead. I got to love the resiliancy of the wood after my first high speed encounter with the sand on a tight reach. We were heeled well over and the board took a huge twisting strain that did not allow it to slide up into the trunk as it would when running aground in a more upright attitude and slower speed. As we came to a stop I felt her suddenly heave as the board straightened out from the deflection it had taken.

Had we had a metal board, it would have been bent.

I doubt that any glass structure would have had the pure guts.

God bless old oak and iron drifts.

There is a certain size pebble, seemingly common around Monomoy when Goblin and I circumnavigated there - to the horror and astonishment of the harbormaster - that could jam the board so well that I had to work underneath with an old hooked pruning saw while my mate banged on an iron rod sent down through the pendant hole.

If you've a board you'll want to go where the water is thin. If you go there, sooner or later you'll go where the seagulls are standing. It helps to be prepared to resolve the little inconveniences that will result.

And that's why we're called the Kedgers' Club.

[Keith Wilson]

Although I'm scarcely an expert in such things (ah, hell, that never stopped me before, did it? ;) ) I'd second the opnion that the bit about the "performance advantages" of twin keels is sales hype. I'll make an evolutionary argument: EVERY go-fast monohull keelboat design has a single deep relatively narrow keel. You'd think if twin biplane keels had a performance advantage somebody else would have figured it out. If I remember correctly there has been some work done on two keels arranged fore and aft, with adjustable angles of attack (America's cup boats?) but that's another thing completely. Twin-keel designs are mainly cruising boats from areas with an extreme tidal range (think Maurice Griffiths, east coast of England) so you can dry out upright.

Bilgeboards (twin angled centerboards) on racing scows are another matter entirely, but they only use one at a time.

[Ian McColgin]

Everything is a bit of compromise. The full length keel so beloved by many of us is not necessarily the fasted foil in the water, but these are sail boats. If speed were the only issue, we'd all be zipping about on hydrofoils.

Twin keeled boats have gotten a bad rep from the mass produced slow pokers, mostly from England, that have the one advantage of taking the ground nice and flat. But there are indeed some that are well designed and the keel wakes do not tangle and trap the boat in her own vortecies.

I do remember running aground on the ebb with a twin keeled boat down below Astoria, OR. The water swirled about us so rapidly that when we were finally dried out, the keels were buried and sand between was touching the hull. Fearing that on the flood we might not float free, we dug like maniacs. As water got around us, he put on saftey teathers and set up a schedule of digging and pushing sand. So we did float free. Might have been a nice day of a leeboard boat like a Golden Ball.

[Stu Fyfe]

A bit about bilge keels. My Bolger 22ft gaff sloop was designed to ground out on the flats of Cape Cod Bay. This design is a compromise. And with any compromise, there is some give and take. This boat does not point very well, but many gaffers don't. She's very fast on a beam reach when the leeward bilge keel is down deeper and really digs-in offering more lateral plane(I hope I phrased that properly). She does pretty well on a run. I've sailed her with Wianno Seniors and she holds her own on every point except to windward. Each design has it's advantages. When I'm sitting up right at low tide, I'm experiencing one of those advantages.

[Eric Sea Frog]

Originally posted by Andrew Craig-Bennett:
I think the name to conjure with, above all others, in keel/centerboarders, is PHILIP RHODES seaworthy, strong, fast, docile and incredibly good looking.Andrew,

A search brought well-done designs but no woodies except rather big-sized yachts.
Are there 5 to 10 meter designs to build?

[Andrew Craig-Bennett]

Eric, probably not, beyond the two mentioned above; Rhodes tended to do bigger boats. But the original question asked about "blue water" boats - in that sector, Rhodes has little competition.

In smaller sizes I think Maurice Griffiths has some quite excellent centreboarders - he was much influenced by US practice. Lone Gull II and Kylix come to mind as very good designs in the sub-10 metre range.

[Dave K]

Phil Rhodes' 23 ft. "Chantey" (keel/centerboard) has to be one of the prettiest small boat designs he (or anyone else) ever did. There is a small scale sail plan in the appendix of Henderson's book about Rhodes, and a more complete look at her in Bray's "Boat Plans at Mystic Seaport". Some nice...

[RodB]

S. S Crocker designed several shoal draft cruisers ( around 36 feet) that were very capable offshore (see "The Good Little Ship".

Crocker's Boatyard has plans available for most of the designs and Sturgis Crocker's Book on his fathers designs shows a lot of them.

Presto type Schooner #291 Dorothy

http://www.imagestation.com/picture/sraid81/p5b3437633b22fe30aff20205450162f3/faf9deb0.jpg

Presto type Ketch 302 Macaw

http://www.imagestation.com/picture/sraid103/p96dc2376f8080eb63381c0c7e3567bcd/f9b19ad1.jpg



Lines for "Dorothy"

http://www.imagestation.com/picture/sraid103/p1135da9cd333a3b91191154e11d310fb/f9b19ad3.jpg

These Crocker designs were cruised offshore and weathered rough conditions very well according to Mr. Gilpin.

RB

[ 02-07-2004, 03:48 AM: Message edited by: RodB ]

[Dave Hadfield]

Those are 2 fine-looking boats! Thanks for posting them.

What does Dorothy draw, 3ft or a little less? And there's even a shoe keel for cast-iron ballast. Great boats.

Tilicum, in the latest WB, is very interesting to me. I'd call the lines more pugnacious than sweet, but it would be a very practical boat to have, and perfect for the Bahamas and Turks.....

[Dave K]

Smaller, but still lovely and shoal, is Crocker's "Sallee Rover". While I would love a "Macaw" (36 ft. ketch), the "Sallee Rover" is as much as I can dream about with any semblance of realism. I have been playing with ideas for a "simplified" version of this one for some time now - maybe when my long lost rich uncle decides to make amends for all these years of neglect...

[Frank E. Price]

Didn't MG eventually decide, after experience with both, that he preferred twin keels to a centerboard? Or not.

Can't address the issue from any experience of my own, but I can say that I think cruisers place too much emphasis on windward "performance." Provided a boat will go to windward in a blow, how fast or how close is less important than most of the other factors in deciding on a hull and rig type, to me.

Frank

[Dave K]

Yes, I agree that the racing scene and its emphasis on "going to weather" to the neglect of many other virtues has impacted cruising too much. Griffiths liked bilge keels, but in Britain many boats lie over and dry out at low tide - with uncomfortable results for inhabitants. The bilge keels allow a cruiser to dry out pretty level and that is much more pleasant. I have some bilge keelers among my favourite designs also - Mike Field owns one of the designs I have liked for years. If not drying out, a centerboard likely allows a bit less wetted surface and can allow a deep fin for windward work when needed. That centerboard yawl rigged "Sallee Rover" still looks nice...

[Daniel Wolf]

I own a West Wight Potter with a swing keel/centerboard, and though I have not experienced washing-up into the cabin when sailing hard, I have heard and read that that is a typical problem, at least with Potters. My boat doesn't spray b/c the former owner, Ralph Saylor, redesigned both the well and the top of the board, so that wash gets bent around and sent back down. If anyone would like to see a copy of his plans, I could scan and post them. (The manufacturer sent him a letter praising the design.) In an article by a Potter owner about his voyage on one of the Great Lakes (Superior I think) during a heavy storm, which almost killed him, he referred to the large amounts of water that came in that way, and to Ralph's innovation that he wished he'd had.