Floating small boats

[jwaldin]

Was looking at another forum about floatation and the question that came to mind is what is meant by floatation in small boats?
It appears that there is a difference in perception between floatation to keep a small boat from sinking and floatation that keeps a swamped boat high enough in the water, right side up, (that's another issue)to enable an adult to slide back into the boat and be able to bail it out so they and or more passengers can get back in.
Over time I've purposely swamped boats, under ideal summer conditions, all with built in floatation by the manufacturer.
I tried a couple of Sabots, a Davison 12, a few little tenders, a Palesman canoe. As soon as I got in they simply sunk further. These small boats all carried the implicit understanding from the manufactors that because they had built in floatation they would float upright when swamped and the occupent could get back into them presumably over the transom and they wouldn't just go down deeper into the water.
My question is has anyone been able to get in a swamped boat and pail it out. If so, what type of boat was it?
I'm not referring to rerighting a little sail boat like a Sunfish that's supposed to capsize a few times a day and then it's righted by walking up the center board.

[Tim B]

I have heard the differences you describe as having floatation (the hull will not sink after capsize, allowing something for you to hang on to while waiting for rescue) versus self-rescuing (having enough floatation in the right places to allow the victim to sit inside the boat and bail it out or paddle it waterlogged to shore.) It takes alot of floatation to be self rescuing, hence it will probably be in a decked boat like a sunfish. Optimist dinghys are open boats (8 foot prams) that carry enough floatation to be self rescuing. Usually it is in the form of 3 large air bags that are strapped into the hull. Optimists are used as sail trainers for young sailors (<11 years old) in many yatch clubs.

[Dave Williams]

jwaldin,

Look over in building and repair. This discussion is going on as we speak.

I put in my 2 pennies worth over there but may have more to say if anyone cares to listen. I have been through this over and over and over with a couple open boats used pretty adventurously in your part of the world by the way.

[NormMessinger]

Well, lesseee. You have your own PFD and throwable floatation devise to keep you afloat. I wouldn't think it would be necessary to be able to sit totally upright or to stand to bail. How much extra floatation would one need in a small boat to account for the bailer?

I have not swamped our Devlin designed Egret (15' open) so I can't say how high it will float without a person in it. I can tell you how fast Lynn can get on the top rail when the water starts to flood over the lower one. And I would suggest a bucket makes a better bailing device than a couple of shoes....

[Meerkat]

The CG has specific requirements for flotation and it includes a provision for floating with occupants aboard.

This came up awhile back and some links where posted. One CG link showed how to calculate flotation requirements for various types of boats and said what had to be included in the calculation and their densities. Engines are one included item.

[mower]

I've swamped my Penobscot 14 and was able to right her, climb over the transom and have enough bouyancy to keep her riding high enough in the water to bale her out. Just one suggestion. Remember to have whatever you use as a bale bucket tied of somewhere in the boat. It's really frustrating to watch your bale bucket blowing out across the waves as you are trying to keep other necessary items in the boat while righting her.

[Dave Williams]

Norm,

I would have to say that if you are sitting in your swamped craft and counting on your PFD to contribute to her floatation so you can bail; then there is a big crisis. Or maybe you were just goofing on us.

Once again I'll say to all. Try swamping your boat! You won't like it! And don't cheat. NO standing on the bottom, no calm warm and sunny day.

[ 12-19-2003, 05:50 PM: Message edited by: Dave Williams ]

[John B]

I rescued a guy who had flipped his 12 ' tinny while out fishing. It was uside down, still anchored, and he was hanging onto the back of it. He was blue when we got him because it was just coming on for dusk in autumn and he'd been there an hour or 2. It rolled over Ok and I got in it and baled it out. gunwhales were a inch or two above the sea. It was the first few bucket loads that were important. :D
and we used to flip our boats all the time when we were kids on. They all had bouyancy built in for that purpose.p class trainers through to javelins.

[ 12-19-2003, 06:21 PM: Message edited by: John B ]

[ion barnes]

Hi John, Canadian Small Vessel Regs say that the floatation must hold the lowest point of the gunnel, with the boat level, and the maximum live load on board. The live load is based on the idea of one body per thwart. A six foot dinghy is expected to carry only two people and a nine footer could carry perhaps three if the design permits. Obviously small wood boats will could support some of their own weight and the weight of the passengers is calculated at about 130 pounds because when swamped, you dont weigh as much as dry. If one were wearing a PFD, it is not added to the mix but it would help as it does add to the floatation side of the equation.

The one point that is missed ,more on larger boats rather than smaller boats is the fact of bouyancy placement. Very often it is placed in spots that are of little use for other things and this means in the lowest parts of the vessel. When swamped, these boats have a tendency to flip over because the center of bouyancy is lower than the center of gravity. Ooops-a-daisey!!

[ion barnes]

Sorry, I am tired and cant read or write.

My first sentence was to imply that the gunnel must be kept above the water with the boat level and maximum live load onboard. Ion

[Todd Bradshaw]

This comes up from time to time on the canoe building boards in the form of the questions "Why should I put extra flotation in a wooden canoe that won't sink anyway?" or "Why does my so-called unsinkable canoe go straight to the bottom when I swamp it and stand in it in two feet of water?" This is the way that I understand it and hopefully one of our real boat designers will correct anything that I screw-up.

I think that along with the prevailing local regulations, whatever they happen to be, the real key to the issue was actually explained in an old episode of "Star Trek" when an alien robot looked at the crew of the Enterprise and called them "Ugly Bags of Mostly Water".

In the past, it was not uncommon to see ads for small boats which declared that the boat was safe, since it would not only float when totally swamped, but also "support" the weight of her crew. The trick was often that the crew was in the water and hanging onto the gunwale. As any lifevest maker will tell you, it only takes around 17 lbs. worth of flotation to support a person in the water since, like it or not, the robot was right and we are bags of mostly water, ugly or not.

If our two-person canoe or dinghy can support it's own weight when awash, displacing an additional 35 lbs. or so to keep the crew up doesn't take much in the way of additional cubic inches of buoyant stuff and can be accomplished with a couple small tanks or blocks of foam if the reserve isn't already contained within the existing structure.

The problem starts when one of those people climbs in to start bailing and begins to raise up out of the water. Any part of your body which is raised above the surface quickly returns to it's actual weight and as soon as you have raised up enough to overpower the hull's modest buoyancy reserve, the whole boat heads for the bottom - at least until you have sunk down enough to return to your in-water weight. At that point the boat will start to come back up.

A bit over half a cubic foot of foam should support two 17 lb. people who are in the water and hanging onto the gunwale, but if those same people actually each weigh 150 lbs. it may take 4-4.5 cubic feet of foam to allow them to climb back in and raise goodly portions of their anatomy above the water's surface so that they can start bailing without sinking the boat. A box-boat like a Sunfish can easily have that much foam or trapped air in the hull, but on an open dinghy or canoe, it's pretty hard to hide. If the boat has it, you'll see it.

I don't know what the current regulations are here for commercially built boats. If the swamped hull only has to support the crew and give them something unsinkable to hang on to, the tanks may be pretty small or not even need to be there on cored or wooden constructions. On the other hand, if enough flotation is required to allow the crew to board and bail a swamped hull, it's going to have big float tanks or some sort of thick, hollow or foam-filled hull.

[Venchka]

Originally posted by Dave Williams:
...I put in my 2 pennies worth over there but may have more to say if anyone cares to listen. I have been through this over and over and over with a couple open boats used pretty adventurously in your part of the world by the way.I would like to know, especially the parts that pertain to Vancouver Island or thereabouts.

[Meerkat]

Originally posted by Venchka:
</font><blockquote>quote:</font><hr />Originally posted by Dave Williams:
...I put in my 2 pennies worth over there but may have more to say if anyone cares to listen. I have been through this over and over and over with a couple open boats used pretty adventurously in your part of the world by the way.I would like to know, especially the parts that pertain to Vancouver Island or thereabouts.</font>[/QUOTE]Venchka; Not sure what you're asking here, but even in summer, the water temperature is about 40-50F. Hypothermia is a big worry.

FWIW, I've read and heard that the western side of Vancouver Island is a risky place to sail. It's almost always a lee shore, has some nifty rock formations (lovely to look at, terrible if you're holed) and the weather is quite chanagable in most seasons. Art Read (at least) might be able to give a more informed picture.

There are some interesting tidal races on the eastern side. You just have to wait for those to be on your side - wait for their direction to be the direction you want to go.

[On Vacation]

I read this ROT crap every week here, pertaining to sealed flotation chambers. Think about something here, for a minute. In plywood what happens the inner cores, of plywood not glassed? Aren't these wooden cores that are encapsulated? The same darn thing when you glass and encapsulate a piece to plywood, for the hull, to allow for the face core to last longer from the elements. When the face core weathers, and deteriate, so does the inner cores.

The same principle applies to a sealed box area, glassed in the form of a chamber for foam. Even if you just close up the box, with no foam, yes you will get some mould, but this mould, is surface mould. The dampness does not penetrate the PROPERLY GLASSED WOOD, OR PLYWOOD, AS IN THE INNER CORES OF THE REGUALR PLYWOOD, WHEN THE SURFACE IS PROPERLY SEALED, OR PROTECTED BY A COATING OF GLASS.

You can eliminate the amount of dampness created in the sealed box, by keeping it air tight, or filling it to the rim with foam upon the proper job of sealing the wood. The biggest problem with mildew and mould in lockers is stale air, or the lack of circultion of fresh air, to move the existing air. The green house effect from overhead and hull temperature changes, has the effect on the non-moving air, that creates mold, and rot upon the damp wood, never drying out, the same principle that you have when dampness penetrates a layer of wood, and never gets air and a chance to dry out.

Think about one more thing, here. What happens to a cold moulded hull, laminated with three to four layers of plywood, or even solid veneers, if water doesn't get through to the inner cores. Same thing as a properly glassed in box for foam filled to the rim.

[ 12-19-2003, 10:45 PM: Message edited by: Oyster ]

[Venchka]

Dave said he had information to share and I would like to hear what he has to say.

Yes, I am aware of the water temps., fog during the warm months, tide races, whirlpools, the West Coast is dangerous (Port Alberni to Bamfield would be interesting), the need for a Mustang suit, crowds in Desolation Sound, logs, cruise ships, etc. and a zillion things I don't even know about yet.

It's all part of the plan.

[Captain Pre-Capsize]

When Todd talks, I listen. He's da man! Who needs to go to school? Just look up any Bradshaw post... ;)

[On Vacation]

This just happens to be an upgrade that I am doing on my own personal hull, to modify the layout, since my kids are now all grown. This had seats in the rear, with flotation sections under a storage area, and outboard the stringers, between the seat top, and the deck on top of the stringers, leading fore and aft, completetly encapsulated with fiberglass, awlquip fairing compound, color pigmented resin, and then gel coat, on the pigmented resin.

I used the worse of the worse, so to speak, as sometimes stated by me and others here, for materials, for a test nine years ago. I used eight dollar luan, 1/2" foam board for the deck, with some modifications to the supporting grid in the sections, a combination of blue board and foam combined to save money and to use what I had around the house, and shop. You will notice that there is some sections of bare glass, outboard of the stringers, where I have removed the foam, in certain areas. It will pop right out with just a light coat of primers or a coat of gel coat, on the resin.

But in the stern, I took out the seat tops, as I am changing the back sections, and cut up part of that deck area to inspect the condition of the foam under the deck, for any moisture, for my own benefit, also. Safety is a big concern when I am fishing the inlets, on the wrong tide.

A fancy dancy four stroke outboard and the time it takes to put together a hull, both is very hard to replace, along with my life in fall and winter fishing season that we fish in here. I want to be able to be awash, at least, to fish another day.

If done properly Rot is not an issue. You can minimize your costs but don't cut steps out, when it comes to your life, first and second your boat. Plan accordingly, so the boat looks like a nice boat, that was thought out, not like you are attempting to make up for a missed step in your ealry planning of construction.

Complete section.
http://www.imagestation.com/picture/sraid92/pdecbf3395cdc454da2970caedcba5c81/fa5859ac.jpg

compartment.
http://www.imagestation.com/picture/sraid75/pc40c14be6c68cfbcaa760c4cd7c78b53/fb513675.jpg

Box
http://www.imagestation.com/picture/sraid92/p9682fde7897ab904ed0220eb837956d4/fa5859eb.jpg

glassed plywood.
http://www.imagestation.com/picture/sraid92/p95b72972438f4cc5ff0b73d3d2e49acd/fa585a9b.jpg

http://www.imagestation.com/picture/sraid93/pae2b893d71e5206530ca67bd2bf6f3a6/fa40952c.jpg

[Frank E. Price]

The concern around here is mostly that folks' tin outboard skiffs have enough foam in the stern to keep the powerhead above water when the boat is swamped by rain. Factory skiffs generally have it, unless an over-specifications motor is hung.

My own skiff being wood and sans motor it's not a problem. I have a 5 gallon bucket on a lanyard I can fish out and bail from the float until the water is down to where I can climb in. If I should ever get swamped by salt water rather than fresh I would apply the same technique from in the water alongside. But sure hope I never have to; the water's right chilly at 55.40N.

I've always figured that if I really felt the need for more positive flotation I would lash four to six air-filled fenders to the thwart risers. But haven't tried it yet.

Frank