Inboard Launch "Victor Slocum"

[John A. Campbell]

After much soul searching and agonizing over my next project, have finally decided on building the "Victor Slocum" by William & John Atkin. This boat can be seen on page 97 of Woodenboat no. 113. Newage Transmissions, Ltd. makes a neat little gearbox (PRM80) and I plan to use a Honda V-Twin gasoline engine of 18 hp (or possibly as much as 24 hp). I now have the plans in hand....she will henceforth be known as "Victoria Slocum" in keeping with the correct gender for nice boats. Has anyone out there built this boat or have any info on it? I have already been in communication with John Bradbury and he likes the boat.....are there any others?

[Keith Wilson]

Nice boat! Here it is on the Atkin web site. (http://www.boat-links.com/Atkinco/Utilities/VictorSlocum.html) It looks a lot easier to build than the standard Jersey Skiff with the box garboard.

http://www.boat-links.com/Atkinco/Utilities/images/VictorSlocum-1.gif
http://www.boat-links.com/Atkinco/Utilities/images/VictorSlocum-2.gif

[ 04-13-2005, 09:28 AM: Message edited by: Keith Wilson ]

[John A. Campbell]

The Honda GX670 can be seen on www.honda-engines.com/gx670.htm (http://www.honda-engines.com/gx670.htm) This engine is 670 cc displacement V-Twin cylinder and is rated at 24 hp max., 21.5 recommended.....at 3600 rpm. Torque is 37.5 foot pounds at 2500 rpm and I plan to run her no more than 2800 rpm at any time. I am in communication with American Honda to determine maximum permissible fore & aft shaft angle that this engine can tolerate (the "Victor Slocum" shaft angle is 7 degrees.) Also I am asking American Honda for info on recommended exhaust methods and exhaust pipe sizes, tachometer recommendations, and temperature gauge connections. The engine weighs 95 pounds dry and the gearbox weighs 24 pounds. I have also asked Newage Transmissions, Ltd. for assistance in assuring torsional compatibility between the engine and gearbox and recommended engine rpm when shifting from forward to reverse or vice versa......they have responded by furnishing me with name and address of a fellow who is knowledgeable of the torsional issue and they have suggested around 900 rpm for shifting.

If any of you have suggestions on any of this, I would really like the benefit of your counsel. I fully understand that an engine of this much horsepower may seem like overkill but I wanted to be able to operate this boat without the engine excessively laboring plus I also wanted an engine that could possibly be used in another boat in the future should the need arise.

[John A. Campbell]

And one more thing...........the Newage PRM80 is $760 plus freight and applicable tax and is available from Lakewood Yacht Service in Seabrook, Texas. This gearbox requires a RIGHT HAND ROTATION propeller (prop spins clockwise when in "forward").......somewhat unusual, I thought.......but perhaps because of the "cone" method of engaging the gear train. The PRM80 will tolerate a 15 degree fore & aft shaft angle.

[dmede]

John,

I am also planing to build the Victor Slocum, though not for a year at least. Ive done some preliminary investigating into drive setups but you seem to have that well in hand. I will be very curious to hear how the build goes, especially in terms of engine, tranny and shaft setup.

Here are some of the links I have gathered for this project (just in case you dont have all of these yet):

http://groups.yahoo.com/group/AtkinBoats/

http://zf-marine.com/ZFR/index.cfm?CFID=4500881&CFTOKEN=89605647&CFApp=1&&CFIDC=NRU2

http://www.buckalgonquin.com/

http://www.glenwoodmarine.com./

http://www.glen-l.com/books/b.html

http://www.glen-l.com/inboard/8intro.html

http://www.marineengine.com/

Take lots of detail pics (if you don't mind) and keep us informed. I think this is one of he best looking small boat I have seen and cant wait to see one being built!

Dave

[dmede]

John,
I have a few questions about the boat and your plans for construction if you don’t mind?

1) I don’t have the plans yet, so could you give me your impression of how complete and well drawn they are?

2) Are the steam bent frames bent over the building jig before planking or laid into the boat after planking?

3) Do you plan to build traditionally or glued ply lap?

4) How will your gearbox hook up to your engine (direct shaft input, output shaft of engine coupled to input shaft of gearbox, coupled off a flywheel, does it need a bell housing)?

Thanks for letting me pester you. I can’t believe how excited I am someone is building this boat!

Best of luck.

dave

[John A. Campbell]

Dave, the 7/8" X 7/8" steam bent frames are spaced on 8" centers but since I plan to build in glued lap fashion using 9 mm Okoume, I plan to use laminated ash frames, one per mold (there are 9 stations). The molds and frames will be the same thickness (1" - 1 1/4") and attached to each other with small steel plates on the sides, screw fastened, and when planking is complete, remove screws and plates, and lift her off the jig. I plan to use full-length ribbands of doug fir or Sitka spruce set into notches cut into the frames to allow me to use Tom Hill's method of planking where the ribband is used to guide the hand plane. I really like Tom's method as it also lets you plan the plank lines very carefully. These ribbands will, of course, remain as an integral part of the hull. I realize this sounds like a lot of extra work but I want this boat to be absolutely perfect in all respects......I'm retired (Sprint) so time required to build it is not important.

In the matter of engine connection to the transmission, I'm just now getting my feet wet. There is a gentleman in Great Britain (a
Mr. John Wilson) who has been recommended by Newage Transmissions, Ltd. as knowledgeable on the matter of assuring torsional compatibility. I will be writing him a letter of inquiry today and will keep you posted on what he has to say. It would seem practical to simply connect the two units with a Lovejoy coupling so long as the BASE on which the two units were mounted was a perfectly flat and stable milled surface or were referenced (bolted) to such a surface. I really don't see the need for butting the two units against one another with an adapter plate but may get my mind changed on this after talking with Mr. Wilson. I have an experienced machinist friend in nearby Temple, Texas who can handle whatever machine work is required. In any case, I will be using professional advice in the matter of tieing the two units together.

The drawings of "Victor Slocum" are quite adequate but will, of course, require lofting which is one of my favorite aspects of this craft. It is certainly understood that 24 hp is overkill for this boat (plans call for a 6 hp Palmer "Baby Huskie" now extinct) however I like this engine, it is very quiet, weighs no more than 100 pounds, and like all engines, has a throttle so I would operate it a speed of around 12 mph and would not expect the engine to labor at all!! The engine will be operating in open air.....no engine box will be used. The gear ratio for the PRM80 is 2.04:1 for forward and 2.5:1 for reverse. Will keep you posted and hopefully will learn how to attach photos when accessing the Forum...........thanks for your interest!!

[dmede]

John,

I like your construction method, it sounds similar to what I have been envisioning, if not a bit more involved.

It’s hard for me to speculate on construction with only the study plans, but I thought I would build glued-ply lap as well. 9mm sounds right. I was also thinking of installing ribbands set into the molds to line off the planks and guide my plane for the laps. But instead of making them part of the boat, I would leave them on the building jig (I’d rather see the line of laps inside not the battens). I would cross brace the boat from sheer to sheer in a couple places when complete and pull the boat before installing frames. Flip it and then steam bend in the frames to be attached through each lap with bronze screws. Or if I wanted to simplify the jig a bit more I could leave off the ribbands and have the molds sit behind the station lines so they wont need to be beveled (per Greg Rossels method in Building Small Boats).

Since it’s glued ply it wont need all the frames, so I could either do every other frame per the plan frame centers, or come up with my own spacing. It works out to be 10 frames if you do every other starting from the first fore or aft frame. This assumes there are no frames bent in where the inwale meets the breasthook or stern knees.

Placing the frames over the molds might be an issue since it looks to me from the study plans that the stations are not spaced evenly. The two fore and aft stations have shorter spacing than the rest and that might complicate adding blocks to the inwale to replicate the frame tops for those I skip.

I’m writing this more for my own benefit but if you have anything to add or comment on please feel free.

dave

[ 04-14-2005, 02:56 PM: Message edited by: dmede ]

[John A. Campbell]

Dave, have been thinking about the idea of steam bent frames and, since I have to work alone (my wife died last year), I think I'll stick with the laminated ash frames and permanent ribbands with radiused edges on the inside. These permanent ribbands follow Arch Davis' method (at least I THINK they do) and should add a lot of stiffness and strength to the hull at very little increased weight. I was also toying around with the idea of not using separate molds at all but simply use the laminated ash frames supported at each frame with a cross spall with a pair of sturdy legs on each cross spall. It would seem that laminated ash frames sided 1 " and molded around 2" supported with cross spalls would be more than adequate to withstand the rigors of planking. The cross spalls could then be sliced off with a thin kerf Japanese dozuki pull saw after the little honey was turned right side up. Maybe I'm overlooking something.......somebody speak up if I am.

I like your idea of evenly spaced frames......only adds one more frame and will probably look much better because of the even spacing.

Will be finished with "Piccolo" by end of the month......am really getting fired up to loft the V.S. ..........have gone from "Victor Slocum" to "Victoria Slocum" and tried to call her "Victoria's Secret" but my lady love Barbara said that might not be such a good idea so ........"Victoria Slocum" will just have to do!!

[John A. Campbell]

I am in need of some assistance in the matter of adapting a Honda GX670 V-Twin 24 hp gasoline engine to the Newage Transmissions Ltd model PRM80 gearbox. I want to operate the two units in "stand-alone" fashion, that is.....engine and transmission both mounted to a milled steel surface (engine mount) , perfectly aligned and with a coupling between the two units and another coupling between the gearbox and driveshaft. I think a Lovejoy elastomeric coupling MAY be the way to go and Lovejoy can do a Torsional Analysis which, as I understand it, will reduce or eleminate gearbox rattle and possible damage to the gearbox. Newage Transmissions Ltd provided me with Mass Moment of Inertia figures (lb. in^2) for the PRM80 as follows:

2.1:1 ratio = 3.89 (rev. = 2.95)
2.5:1 ratio = 3.18 (rev. = 2.66)
2.94:1 ratio = 2.68 (rev. = 2.48)

I am certainly not a mechanical engineer but it would seem likely that before the engine-to-gearbox coupling can be selected through a torsional analysis worksheet, the Mass Moment of Inertia of the drive shaft and prop (assuming 10" diameter, 10" pitch, 3-blade) would have to be added to the figures given for the gearbox. Also, the same MMOI for the shaft and prop would have to be known before the coupling between gearbox and drive shaft could be selected. I asked Newage to include this in their email response to my inquiry and they chose to ignore it or perhaps I didn't provide them with enough data about the boat although I did describe the hull shape, weight, and all particulars known to me about the project at this time. So my question is: How does one calculate the MMOI for the drive shaft and prop as described above?....And isn't it correct that this figure should be added to the MMOI for the gearbox?

I would appreciate hearing from anyone who can help me with this............many thanks in advance..............John

[John A. Campbell]

Thanks, Ironmule, for the reply........that stuff is way over my head.........I think I'll call or email Michigan Wheel and ask them the questions. Being marine prop people, they should have the answer......hopefully.

[dmede]

John, I have been pouring over my plans for the VS for a while now and have given this particular problem the most thought.

I also plan on using the PRM 80 gearbox coupled in line with whatever motor I end up using (I’m looking at the Hatz 1b and the Yanmar L series motors). In my case I think I will mount the PRM 80 directly to the motor via two steel plates welded to each other with spacers. One plate will be drilled for the mounting holes on the PRM the other for the mounting holes on the motor and each will be bolted in accordingly. The PTO shafts from the gearbox and motor will be coupled in the open space between the two plates. It will probably be a pair of flange couplings bolted to each other (maybe with a rubber cushion style flex disc between them). I imagine I will need to have the flanges custom made.

The PRM and the motor will act like one unit once they are bolted together so I can then bolt just the motor down to the engine beds. If the gearbox proves to heavy to have bolted to the motor in this way I would add a common engine “sled” to bolt the PRM to via its side mount holes. The “sled” would just be angle iron cut to the engine bed length with mounts welded on to reach up to the PRM and bolt thru it.

My impression of this type of set up is that it doesn’t require exact tolerances since the motor I’ll be using is so lightly powered (7-10hp in my case). If vibration becomes an issue I could change out the engine beds, add adjustable shock absorbing mounts to the motor and PRM and use a flex coupler between the PRM and the prop shaft.

This probably makes no sense with out pics. I have a mock up I made in Illustrator that I could email to you as a PDF if your at all interested.

This is all speculative at this point. I’m primarily interested in comparing notes since I suspect you’re further ahead of me in planning at this point.

Dave

[Meerkat]

A good name might be "Victor Victoria" ;)

[John A. Campbell]

Dave, I sorta got side-tracked on finishing Piccolo and lofting Victor Slocum. Received a call from my 9-year old granddaughter about 4 weeks ago wanting me to teach her how to build a boat and so now I'm waist deep in completing a 7' 7" "Nutshell Pram". She'll be paying me a visit in a couple of weeks and we'll finish construction and paint it, etc.

Sounds like you've got a good idea about the steel plates.......since the input shaft on the PRM80 is splined, that may present a problem. And the coupling (assuming an elastomeric type) will have an overall length of 4 inches or more so the two plates will be fairly far apart. I've decided to let Lovejoy Company help me with the coupling issue......hopefully they will have a coupling which will match the splined shaft on the PRM80 on one side and a smooth shaft with keyway on the other. Sure would like to see your sketch of your plan and I'm also leaning toward a more sensible powerplant like the one you're planning.....something around 10 to 12 hp w/electric start.......preferably Honda because they're smooth and quiet.

[Tom Hoffman]

John, I e-mailed you directly about the Whitehall that you were asking questions about. Did you get it, I used the e-mail that you have listed here on the site. If not, e-mail me at tomhoffman@starband.net and I will resend it to your other e-mail address.

Tom...

[Ric_Bergstrom]

Both BMW and Mercedes have very nice rubber couplings in their drivelines. On the mercedes the coupling in front of the rear diff on an E320 (try late 90's ) springs to mind and the BMW on a 80's 3 series in the driver shaft.

Either would last near forever for your useage and they would tolerate alignment issues. You may even be able to use the plates from the shafts with some creative engineering.

BMW calls theirs a GUIBO. No idea what that is translated.

For example http://e30m3performance.com/installs/installs-2/guibo/

[Stiletto]

R&D drivetrain make flexible couplings for a range of marine applications. A quick google search brings them up.