Got a new sailing dinghy

[Davidasailor26]

With the extraction of 66 copper rivets and 2 wood screws the the old gunwales have been removed. I cleaned up the edge a little so it’s just about ready for installation of new ones.

(The straps are there to help keep the hull in roughly the right shape.)

Building new gunwales looks like it could be a bit of a project. It’s a complex curve, with the wood twisting to match the angle of the hull at the bow. The radius itself is manageable but the twist is tough. I was able to salvage enough of the old piece to use as a template for a jig, and my dad and I built one.

Unfortunately we couldn’t get at 1/8” strip of wood to make that twist, even heating and steaming it with an iron. We eventually got it mostly flush against the jig but then it started to split in one spot.

I did call Dyer Boats, who apparently still makes the boats and sells replacement parts. They were super helpful talking about various aspects of the boat and how to go about the restoring it. They do sell replacement gunwales. With shipping they’d be just over $350, and building them ourselves seems like the more rewarding option if possible. Short of building a steam box though I’m not sure how to make it work. The only other idea I had was to laminate as close as possible to the jig, then put it against the boat over some packing tape, and cheating by using some thickened epoxy to fill the wedge shaped gap that will be on the most twisted section.

I think I did solve the mystery of the centerboard seal. I described what I saw to Dyer and they were thoroughly confused, because they only put a seal on the lever, which was just supposed to seat against the trunk. So I poked at the trunk some more and the extra gasket did come off. It looks like the gasket on the trunk was actually the gasket from the lever, and it just got stuck to the trunk somewhere along the way. So just a little cleaning up of the silicone remnants on the trunk and a new lever should have the boat water tight again.

 

[PaulK]

I took oak strips and boiled them for the stems on our kayaks. A steam iron is not going to cut it. It's not long enough exposure to get deep into the wood grain. Your curve is too big to fit into a stovetop pot. A simple wooden box though, held together by drywall screws with a hose from a big teapot stuck in one end and run for an hour should turn 8'x1/4"x3/4" strips into so much spaghetti. It would probably be best to clamp the strips into the jig unglued first, so they can take the shape, dry and cool off before laminating them with epoxy. It could get messy otherwise.

 

[TomY]

Maybe you need to rip slightly thinner strips. I think the bend for my dinghy was more severe. I used Douglas Fir and don't recall any problems. You may need a solid bending form as yours presents hardspots.

I copped this image off the web: In this Nutshell frame, the lamination is glued up to about 2" thick. Then a pattern is marked on the outside and the cuts made for the bottom, planks.

The $350 sounds like a good deal but if you want to try steaming (strips or a solid gunwale), I'd use a piece of PVC pipe for the steam box. Easy to get just slightly larger diameter and length than you need for your stock. A tea pot on a burner piped into a hole in the PVC is all you need.

 

[jssailem]

Lou the Shipwright on the Total Boat website provided all sorts of old school tricks.
Here he discusses compression bending and a steam bag.

 

[shemandr]

View attachment 188478

That's a lotta clamps. Awesome! Checkout the details of that jig.

 

[Hayden Watson]

Andy at Boatworks Today has just finished a dingy paint projest that turned out very nice. The process begins here.

 

[Davidasailor26]

Andy at Boatworks Today has just finished a dingy paint projest that turned out very nice. The process begins here.

I saw that. I’ll definitely be applying lessons learned from it.

 

[jssailem]

That paint job he did on the hull was spectacular. As he declared, quality paint work is in the preparation of the boat.

 

[Davidasailor26]

Well, I can’t say our first try at steam bending was a great success -

Some lessons learned from the first experiment -

• Our steam box of 2” pvc pipe works just fine for this size wood. It easily stayed at 212 for the 50 minutes we steamed the 3/4” board. We do need a better way to support the pipe so it doesn’t bend when hot.
• We used kiln dried red oak for this experiment because that was all we could find quickly. Wetter wood would certainly work better.

For experiment 2 we might try pre-soaking the wood in water with fabric softener which supposedly helps overcome the kiln drying. We’ll also probably increase the steam time, and rearrange the supports on the jig so we can push the wood onto it rather than pulling into it.

I did make some progress on the inside of the hull. I cleaned up the backboard on the transom and lightly sanded the rest. I also ground out some bevels around the 23 small holes on the starboard where there was originally some kind of mounting bracket, so they’re ready to be patched with glass.

 

[jon hansen]

red oak? in a boat? david, i hope i'm wrong, i have always heard that red oak rots very quickly in boats. worth checking out though.
i hope i'm wrong, prolly wrong, but that is what i have always heard.

 

[Davidasailor26]

red oak? in a boat? david, i hope i'm wrong, i have always heard that red oak rots very quickly in boats. worth checking out though.
i hope i'm wrong, prolly wrong, but that is what i have always heard.

Not to worry - Red oak is not the final plan. This was just a test piece to see how the bending would work and how the jig would line up to the hull. The final solution, assuming we can get the bending to work, will be white oak, which is the same as Dyer uses.

 

[dLj]

I think white oak bends better. Also, did you bend in a compression frame? I didn't see one in your photo.

dj

 

[Captain Larry-DH]

Nice progress on the hull. Why not use thin strips glued up into a laminate with epoxy with a plywood form? Easy to bend and clamp while it sets up, no hard spots in the bending process.

 

[Davidasailor26]

I think white oak bends better. Also, did you bend in a compression frame? I didn't see one in your photo.

dj

White oak is generally listed as the easiest bending wood and red oak as second. So yes white would be a little easier but the red shouldn’t be too bad. Figured if we were successful on the red oak test piece that would ensure the white oak would be at least as easy. We didn’t have any way of compressing the outside, which probably did contribute to the split. By flipping the jig around and bending around the outside of the jig instead of the inside we might have more options for that.

 

[Davidasailor26]

Nice progress on the hull. Why not use thin strips glued up into a laminate with epoxy with a plywood form? Easy to bend and clamp while it sets up, no hard spots in the bending process.

We did try strips at first. The problem is that the piece bends in two dimensions - left to right for the curve of the bow, but also up and down to match the profile of the dead rise. That’s why the jig needs to start low then go up and down again. The strips, being so thin on one side, easily make the radius from left to right. But they’re still 1” high vertically, so they don’t make that down/up/down shape any easier. Steaming the strips might make it possible to bend in both directions, but then we’re taking about epoxying after steam bending. The other option there is to cut the strips and just bend them in the easy direction, laminate them along with extra layers to make it oversized, and sand to back out the extra width and accommodate the deadrise. But that sanding along the curved surface sounds like a fiddly process.

 

[dLj]

We did try strips at first. The problem is that the piece bends in two dimensions - left to right for the curve of the bow, but also up and down to match the profile of the dead rise. That’s why the jig needs to start low then go up and down again. The strips, being so thin on one side, easily make the radius from left to right. But they’re still 1” high vertically, so they don’t make that down/up/down shape any easier. Steaming the strips might make it possible to bend in both directions, but then we’re taking about epoxying after steam bending. The other option there is to cut the strips and just bend them in the easy direction, laminate them along with extra layers to make it oversized, and sand to back out the extra width and accommodate the deadrise. But that sanding along the curved surface sounds like a fiddly process.

Or, you can laminate square, instead of rectangular, strips. Once you get the long thin square pieces made, you can do some mighty interesting patterns. throw some other colored woods in there. Use you imagination... LOL

Steam bending is really cool stuff to do. But multi-dimensional laminating can do things you can only dream of...

dj

 

[dLj]

White oak is generally listed as the easiest bending wood and red oak as second. So yes white would be a little easier but the red shouldn’t be too bad. Figured if we were successful on the red oak test piece that would ensure the white oak would be at least as easy. We didn’t have any way of compressing the outside, which probably did contribute to the split. By flipping the jig around and bending around the outside of the jig instead of the inside we might have more options for that.

Oh yeah, hickory also bends pretty well.. We used to make the big U shaped neck pieces used for oxen out of hickory.

dj

 

[TomY]

I haven't done a lot of steam bending but I think stock with the grain running parallel to the stock edges is what you want to try to find. That bend certainly isn't that severe for steam bending. Look at Windsor chairs and that stock DLJ posted.

It looks like the grain on the red oak was running out of the stock in that area where it split. Plus as you say, if you could find some straight grained white oak that was freshly cut and not kiln dried, or only air dried.

I'd definitely increase the steaming time. It should bend pretty easily when it's been steamed enough.

Keep trying! This is fun to follow.

 

[PaulK]

Is the curve of the sheer (deadrise) so much that you can't bend the wood to match after the piece is steamed? Attaching it at the bow and torquing the two ends should provide plenty of leverage.
And/or...
if the jig is set up to account for the deadrise, it should be easy to use strips and have each of them "step up" to go with the deadrise as well. You'd then plane down the steps to smooth the rubrail to its final shape.

 

[Davidasailor26]

Steam bending attempt 2 has gone much better so far.

We used the same type of test wood, but left it in for 1:50. Having the jig turned around so we could bend around the outside instead of inside was a big help too. Oh, and we also realized that in our first try we forgot to plane the piece down to the right size, so we had been trying to bend an extra 3/16”.

After the wood relaxes overnight we’ll see how much spring back there is and how accurate the jig is.

For version 3 of the jig I might need to add a couple more supports or make a solid form instead of the posts. There were a couple points in the wood that got a little pinched by the hard spots. We’ll see how they look after it’s out of the jig and go from there. But it was much more satisfying to see the wood make the right shape without breaking.