View Full Version : Alternate planking style help


longfellow
04-16-2009, 08:08 AM
I am lofting a traditional plank on frame, oak floors and solid keel daysailer very similar to an O-Boat. I would like to get opinions on two approaches. First, if I build as designed with 5/8 planks on 3/4 inch square bent oak frames, what alterations to the hull, its seams etc should I do, given that the boat "may" (if I am still on the waiting list for a slip when it is complete) have to be trailered. Now, by trailered I mean only from the yacht club lot to the ramp, not over roads from my home. But still it will be a wet and dry life through the season.
Next if I choose to build the hull using an alternate method of cold molding, then I would like some guidance regarding the specific alternate specifications (number of skins, lay directions, thicknesses... Do I still frame it up as designed? Basically when one chooses the "alternate" method of cold molding when you build (and here I would really appreciate opinions from designers, architects and builders who have actually done this - which is why I am not asking on that 'other' site; too many armchair builders.) what steps to you take? J. Guzzwell's book is a great one for when I actually get to the planking but he offers no design criteria/specifications (for obvious liability reasons I suppose).
Thanks,
Ed

marshmat
04-16-2009, 11:05 AM
Hi Ed,

Dave Gerr's book "Elements of Boat Strength" might be a useful reference in your case. Chapter 11 of that book includes a scantling rule for cold-moulded wood/epoxy construction, including how to determine skin thickness, number of skins, etc. and what modifications to the stringers and frames are permissible when switching to cold-moulding. For $30 or so it's a useful book to have around.

I'm not one of those pro builders who has done such a design modification, so I can't offer much advice specific to your case. To be honest, I think if I were worried about the wet/dry issues with trailered plank-on-frame, I would probably be considering wood/epoxy strip plank instead of cold-moulding, simply because there are so many tales of cold-moulding proving to be more labour-intensive than expected.

PAR
04-16-2009, 08:57 PM
Cold molding is much more labor intensive and requires a fair bit of skill fitting each layer of planking too.

I make conversions like these every so often, it's not particularly difficult.

From a novice builder's view point, one of the strip planking methods, would be a better choice for a wet/dry cycled boat.

Geer's book is helpful, but not all inclusive. It would be wise to have a new set of scantlings worked up for your build.

longfellow
04-17-2009, 11:29 AM
Thanks to both of you gentlemen.
I am not sure how responsive a NA would be if I were to apporach him with the request to modify an existing set of plans, in all likelyhood a set that this same designer did not create himself. I could try it I suppose. I will definately try to pick up Gerr's book through interlibrary loan. As an alternative I may as well ask for some suggestions for designs that are as close as possible to the boat that i am interested in, but originally drawn as a "strip" boat or a ply on sawn and gusseted frame design. I'd prefer not to build a stitch and glue boat or lapstrake ply. Just a preference related to the type of woodworking I enjoy. The design that I wish to build is that of an O-Boat; 16-22 foot daysailer, comfotable, transom sterned, fore deck or small cabin, robust keel or combination keel and keel batten; well-detailed plans are a plus. I located a nice seventeen footer by Edson Schock which I will continue to look at. Thanks.

View Full Version : Alternate planking style help