Wooden Boat People
By McKenzieDriftBoat.com
Gunwale Design Question
Hey there WBP,
Does installing gunwale blocks for the inside gunwale have a structural function? I've seen boats that have attached the inside gunwale directly to the hull without the blocks. Must save quite a bit of time but wondering if this compromises anything?
I am thinking about doing a quick and cheap drift boat build and it seems like doing a simple gunwale is an attractive thought.
Thanks for any ideas on the matter.
-Kelly
Views: 3980
Replies to This Discussion
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Permalink Reply by Dave Z on
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I think the blocks are more for function.. to hold onto the inner rail in "oh sh!t" moments. If you grabbed the outer rail and scraped a rock, you'd lose a finger or two.
Solid rails would be easy, and easy to finish though. I doubt they add structural anything. In fact solid rail might be stiffer.
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Permalink Reply by Lawrence E. Long on
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Dave :
They in fact do add strength to the gunwale. Rather than drag out some of my structural books from school think of it this way. If you laid out 2 16' 2x4s across saw horses one on top of the other. and started loading themup with concrete blocks. Un-nailed they would have the greatest deflection. nailed together would be less. Then if you added 2x4 blocks between them say a foot or so apart and glued them in it would have the least amount of deflection. What you are building is a simple truss. Besides it shows off your craftsmanship and looks good if you use mahogany blocks between white oak or DF gunwales. How are the twin boats comming along?
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Permalink Reply by lhedrick on
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Are you installing new gunwales or just doing some refinishing?
From seeing the photos of the Z I have my doubts of you will build a simple drift boat. I have a feeling it will morph into another show piece.
I have only used spacers on 1 boat. All the others have been installed right to the sides. On the last project I epoxied the inside pieces then bolted through for the outside pieces figuring the outside might need to be replaced one day. I would think the blocks are just an artifact and style which comes forward from the framed world. I would seriously doubt not having them would have any effect and since your boat has bolted oar lock bracket you don't need blocks for sockets.
Sandy over at Montana-riverboats.com has started building up laminated gunwales. He also glasses over the sides and top of the gunwales so they hold up better in the elements. Less oiling or varnishing. Bare wood just doesn't seem to hold finish very long.
I agree also they make a good hand hold up front.
I am glad I kept the finish work on the new boat to a minimum. It's already been scratched by the trailer and the frame of a cat on the beach at Deso. It came home scratched up and I never bumped a rock. The gunwales have gouges in them too. This sport is hell on boats or I might need to learn to row better and park in better places.
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Permalink Reply by Kelly Neu on
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Haha. Larry, you know me better than I know myself. I am sure to go "O.C.D." on this project as I did on the ZIz. Though, this time I've got to pull it off over 8 weekends...
The plan is to build a dory for less than you can rent a raft. I usually rent stuff from University of Idaho Outdoor Program and for 5 days rental of a 16' raft =500 big ones. An even higher goal would be to build a boat for so little that I could just stick it in a bonfire afterwards or turn it into drift wood. No trailering home, no increased gas costs, no storage fees!
We are doing a 5 day trip on the lower salmon in August. The water level will likely be pretty ideal, not too high and not too low and many of the trip goers are dory guides so we can probably pull off some repairs on the river.
I'm hoping to scrounge around for found wood and just screw everything together, very little glue, not so water tight, just one ugly but functional boat. Perhaps an ambitious project for me as I usually like to spend 5 years planning a boat... Not sure if I'll be able to lead this ugly duckling to the pyre afterwards!
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Permalink Reply by chris towles on
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i would think that if you were building on the cheap, framed would be the way to go. scrounge around a couple build sites and see if you can find any scrap cvg or framing fir pieces for building frames and seats. get yourself 2 sheets of as cheap 1/4" marine ply as you can. the hull could be a/c fir with a 1/4 " skid shoe. you could make the logs and gunnels out of one cheap 16' piece of clear framing fir..$20 or less. a box of ss screws, some 5200, a quart of oil porch and deck enamel, boat soup, and your in business. remember, in the old days they build with what they had cause it was cheap and avaialable.
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I have a friend who, with his brother built a dory out of CDX plywood in a weekend. It made 2 or 3 trips down Deso before being retired as a flower planter. It was hauled to the dump before I ever go to see it.
I should be floating the Main in late August also. I will keep a look out for those gold letters.
5 years? I know it wasn't 5 years but how long did it really take to build your last boat?
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Well, I dreamt about building a whitewater dory for about 5 yrs before the time, money and expertise crossed paths. Then I had about a month to think about logistics and materials and then it was building time. It took 10 days to build the hull and about 4 months to build the rest of it. I didn't have any plans for the deck so that part was really fun to build but it took a while. And if I could do it over again I would have oiled the gunwales instead of varnishing them!
Enjoy the Deso! Whew ee, its gonna be rippin. I'll be squeeking along in a big ugly raft on the Rogue. Hope to see you on the water this year.
-Kelly
P.S. hello to your all of rowdy deso crew!
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S
Shame on me Lawrence. You are correct!
The twins are close. 6 hours of work or less left. They are coming to great. I'll be sure to update a post.
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Back to the original question: Blocks between the gunnels do add significant stiffness. In essence they act like a cored panel, the blocks being the core.
We did a line of glass rowboats from a shop where I worked...Wherries, a pram and a Gig...all glass molded from lapstrake plugs, then finished with nice teak thwarts,and gunnels. Without blocks, they were flimsey...we tried one.
With the spacers, they were hell for stout...One of our wherries was rowed from Seattle to SE and another attempted the northwest passage...no go...
Don Hanson
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Don:
Glad to hear my "structural engineering" example is born out by real world experience of a professional boatbuilder with open water skills at the oars. Now don't tell us you ran the Columbia bar. That has to be the one of the most dangerous stretches of water I have ever seen.
Good luck
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It wasn't me who rowed to Alaska. No sir!
Nor did I go along on that attempt to make it across the ice and the polar sea to Bafin Bay, rowing and dragging one of the Blue Heron wherries, though that nut, Jon -something, from Bozeman, he did try to talk me into it. He got stopped by weather and left that boat in some remote villiage. It's still probably stuck in the snow bank, keeping all the broken snowmobiles company..with it's gunnels still intact. He returned the next season and showed us some slides of his journey....Ugggg! Looked awful..
I also have never crossed the Columbia bar.
I did have a nice long talk, at the Port Townsend Wooden Boat show, with George Caulkins, who designed and built a line called the Bartender. ..A Small hard-chined double ender planing power boat. They are highly thought of for use in that nasty type water. Framed marine plywood with a small cuddy cabin and a couple of V-berths. Another boat I'd like to build someday, just for fun.
The yard where I worked was also the birthplace of the Thunderbird sloop. Designed and built by Ed Hoppen, who was still a frequent coffee drinker around the wood stove in the shop after he sold it, that was another very popular hard chined framed plywood sailboat, 26'. Still seen in large numbers around the Puget Sound.
Don Hanson
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