21' Bank Dory build in ply, epoxy and Ipe?

[Tractorshaft]

Hi,

I have ordered the Atkin Bank Dory plans for the "Freda M. Himmelmann". I intend the use the heaviest, thickest marine plywood I can fit into the plans to plank it with, Sapele perhaps and a couple of hard and heavy planks set down low to lower the W/L.

I had the idea to use a very heavy indigenous or tropical hardwood, Ipe, shagbark hickory, black locust etc for the gar board plus maybe one plank. I have heard of people having problems gluing Ipe, locust and hickory but I am going to try the new West GFlex epoxy designed specifically for hard to glue woods to include reliable bonding of white oak and tropical hardwoods. Their white paper on it shows very positive tensile adhesion results with "Hard to glue" wood and plastics. In addition, I am going to put a little 9.9 Yamaha kicker in a inboard well, I don't like to row.

I already have a hydraulic raise/lower system engineered to pick the motor up and back to clear the bottom. I had a 24 foot Opheim dory made of mahogany when I lived in Kodiak , it was setup very similar. The mahogany logs washed up on the beach and Ed Opheim made a very nice dory out of them. The boat was almost 20 years old when I got it. I was not uncommon for tropical hardwoods to occasionally wash up on the beach in Kodiak, I was told by people who would know that they were "Fall Offs" from lumber carriers.

I do know that I want to get some weight down low in the hull and I want to build it out of mostly plywood, except for the stem, tombstone and gar board +1 plank as described above.

Has anyone ever ventured into this territory as I describe it? I think if I can get at least a couple planks set low that have a very high specific gravity, the weight of the little 9.9, a 8D Cat battery in a box to run a few lights, my l/w hydraulic pump and a cigarette lighter I can get it riding low enough in the water to put put around my favorite fishing spots without a exercise in initial and secondary stability. I realize I may have to coax some of the higher SG woods in a steam box to get them to commit to my project, but..I guess if you have to bend a hard board, a dory shape is about as good a shape that you could ask of it?

Am I trying to overcome a non-problem? The Sapele plywood with its .65 to .75 specific gravity seems already heavier than anything but a mahogany planked dory would be?

I also have access to some nice air dried cypress, cheap, that I could do the job with?

Comments not only welcomed but solicited :eek:

[JimD]

....Am I trying to overcome a non-problem? ...

In my humble, quasi-knowledgable opinion, yes. Twer it I I would have a look at similar sized plywood dories and build it roughly to those scantlings in meranti ply, and if it turned out light I would add more ballast.

http://www.boat-links.com/Atkinco/Photos/FredaMHimmelmann/FredaMHimmelmann-01.jpg

[Thorne]

I'll agree with Jim. Some dory plans are opposite of what you propose and have solid wood sheer- and other strakes down to a ply garboard, due to the inability of getting garboard strakes wide enough in solid wood.

Mixing ply and solid wood can be a problem for many hull applications, the exception being some transoms, knees and stems from solid wood on ply boats. I have one such problem boat in the back yard waiting to be worked on -- the solid wood bottom plank has warped and split away from the marine ply hull and laminated frames.

http://www.luckhardt.com/md-bottom1.jpg

[TerryLL]

I agree. Don't mix solid lumber and plywood for the hull sheathing in this boat. You are introducing a ton of problems and difficulty for no purpose.

I built the 23' Cape Ann dory (a banks type hull) many years ago. The bottom was two layers of 1/2" fir ply, the sides a single layer of 1/2". The framing was on the heavy side, the centerboard case bordering on massive. No problems with stability, plenty of weight down low, seldom carried ballast. A 9.9 Honda pushed it nicely. Sailed it from Seattle to Alaska in '84. The boat was very capable and saved my skin several times.

[Tractorshaft]

Thanks for the replies, I appreciate the input. I have looked for information on Cypress as a planking stock, haven't found much online. Does anyone have direct experience with this as a boat building wood? Thank you.

Jerry

[hank woll]

hello-do any of you folks have any insight as to the correct offsets for the coast guard dory?-where did you get the cape ann plans?-what sort of well did you construct?-any help will be appreciated

[wtarzia]

I own an 11 foot LOA Lowell sailing dory-skiff built in 1984. Back then they built their dories with a plywood garboard for the reasons mentioned above (they still may, though the shop has changed hands twice since then as the wooden boat market declined and became problematic, so I am not sure what they do now as a habit). Also, back then, they were still a commericial outfit (200 years old; but later became a museum-shop, and now, who knows? Quasi-commercial-museum?) and had no problems using other modern methods with traditional dories, so they encapsulated the solid wooden bottom and plywood garboard in West epoxy and glass, since most of their customers kept boats on trailers. I have not noted any problems with the ply pulling from the wood, but then, the encapsulation job was quite complete and robust (they really poured the epoxy in there, it seems). The drying-between-sailing issue was real for the solid wooden parts, though -- water tended to leak between the plank laps after a few seasons each time the boat heeled over and immersed the wooden planks since my boat never really had a chance to swell. They put a bead of polysulfide between plank laps, which kept the boat dry the first few seasons, but then the planks did shrink a bit.

(off the topic but interesting: I also got creeping greenish fungus and rot between some solid-wooden plank laps, serious enough that I had to cut out a patch and epoxy in replacement zones between two planks, and try to figure out how to match plank laps. I lost sleep when I saw my pristine Lowell dory so ill, but that was when I lost my fear of trying to work on wooden boats -- I had nothing to lose, now! So you can say that plank-lap rot had a happy ending. Not sure why the planks rotted there -- I suspect because I locked the boat in my garage after sailing and let my car suffer the weather, and perhaps lengthened drying time gave more time for fungus to grow? ) -- Wade

[TerryLL]

Hank,
The info on the Coast Guard dory in The Dory Book is a bit sketchy, but you might get some help if you contact Lowell's Boat Shop (Lowellsboatshop.com). There is a very similar dory with an offset table in Howard Chapelle's American Small Sailing Craft, p.88. The Cape Ann dory I built came from the same book, p. 91. The offset table for the Cape Ann is printed very tiny, but I was able to get enough points to loft the boat full size and develop a new table from the lofted plan. Sadly, my offset table for the Cape Ann has gone missing.

The Cape Ann is a serious beach cruiser, very solid and dependable, but certainly not a performanse sailing boat. The well I put in her was long and narrow to allow the outboard to be tilted up. If I had to do it again I would widen out the transom and extend the well through the transom. Turbulence and exhaust build-up in the well was a persistent problem.

I'm glad to help you any way I can. Feel free to contact me by email.

[hank woll]

hi terry-yes i have seen the pictures in chapelle's book-i was thinking of using plywood for the garboard but i guess it is a bad idea-i have plenty of good white pine-i guess i can find enough wider stock to scarf to length and make it a 5 plank boat-any thoughts?--i know this type of hull has good initial and secondary stability from using one when i was a boy-all my cousins and i would rock grandfather's dory to see if it would go to the gunwale-it never did even with 5 of us to a side-i think the well in gardner's book looks pretty good-i don't want to cut the transom up-i did see one like that in nova scotia years ago-i guess it worked-if you can-reply to my email-woll@empacc.net-thanks-hank