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Early 50's Thompson runabout restore


Scott Dunsworth

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New project, basically a total rebuild, very little is savable. 75% of the cedar planks are good, the hardware and that's about it. There are some odds and end parts like the dash, deck beams that are still usable. Here's some pic's of the general condition.

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I will have to re rib the whole boat, they are white oak. The inner keel is white oak also.

I have made a new mahogany transom this week all it needs now is fairing to fit the boat.

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It came in at 3lbs heaver than the original mahogany transom that was rotted through in a few places.

My plan is to install the new transom, new battens and outer keel. Then start replacing every other rib starting aft and working forward, then start aft again and replace the remaining ribs.

We will see how it goes over the winter. I got this boat about ten years ago and sidelined it till I needed some winter entertainment. The ribs steam pretty easy, the hard part will be not losing the hull shape. I'm trying not to remove anymore planking then I have to, that should help keep the shape.

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I'm glad you noticed this. If I was doing that rebuild I'd have removed the garboard, likely skipped a plank and removed the next, helping retain as much shape as practical. Additionally, when there as bad as I think you have, I'll rip 1/4" (on that size boat) into 8" - 12" wide strips and use these diagonally over the existing planking, again to help hold the boat's shape and stabilize it. I'd also likely build interior frames to push up or pull down on certain areas that seem obviously out of whack. All of this done, before the ribs get removed and replaced. These would be done every other or every third one at a time, also to preserve the shape. The aft most ribs will be the toughest to bend, as that bilge turn on those old sea skiff hulls is tight. The last 1/4 of the hull don't be surprised to break 50% of them if you're not laminating. I've done a number of that style of hull and I usually do laminate, at least the last 1/4, where the turn is tight. Maybe every other one, to save some effort and goo. At midship it gets a lot easier to bend them in as solid stock.

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Thanks for some pointers Parr. I wasn't thinking about breaking any ribs in the aft area. I noticed when the boat was built that they cut the first three ribs in the bow section under the keel, guess there's no way to make that hair pen turn.

Don't really know why I'm doing this, the boat is really ready for the burn pile. Just want to save an old boat and learn some new things that have nothing to do with technologies I guess.

The planks are 3/8 x 1 cedar bead and cove. Going to try and find some cedar locally, if not, I do have access to clear cypress that I used on my cold molded 28. The wood seems pretty similar in weight and stiffness, what do you think?

 

Scott

 

 

 

 

 

 

 

 

 

 

 

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5 hours ago, Scott Dunsworth said:

Don't really know why I'm doing this, the boat is really ready for the burn pile. Just want to save an old boat and learn some new things that have nothing to do with technologies I guess.

 

This is the last place on Earth where you would have to explain or justify working on a boat.  All you need to be able to say is that you think it will be fun, but we already assumed that.  Have fun!  I'm going to watch.

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Never thought about using green wood Ken. I have about 25 white oak ribs already cut they are 1 1/4 wide by 7/16ths thick. I bent two of the easy ones a few years ago by just soaking them a few days. Hoping that they bend even easier steamed.  Read somewhere that soaking them a while before steaming that they will take the bending even easier than just steaming. I have seen red oak soaked where you could just about ty a knot in it. But white oak is a different animal, doesn't soak up water real easy. Red oak does like a straw and will fill up its whole core till its water logged.

The only thing that worries me right now is the bow work. I can see this whole boat would be much easier to build new, than trying to replace stuff in reverse.

Anyway this is a new woodworking class for me

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When bending stock, it's all about stock selection. Avoiding grain run out, defects, using a sheet metal backer as you bend, and green stock helps tremendously. When bending questionable stock (dry, grain run out, etc.) expect 50% breakage in the worst of the aft bilge turn pieces. Even if you use perfect stock, you're going to experence breakage, so have a 10 - 15% over supply of stock (best case). On ribs of those dimensions, you'll get some "bust out" on the outside of the bend (unless quite rift sawn), so back it up with a steel or aluminum strap as it's bent (assuming in place on the boat), to help prevent this occurrence to challenge your inventive cursing techniques.

 

Moisture content is important and soaking helps, but it's the heat that gets the job done, so have a heat gun (a good one) ready, to convince the last bit to go in. Lastly, consider over bending about 10% of the radius in the tighter areas. You'll have some spring back once it's released and relaxes a bit. Placing a 1x2 or 2x4 (or wedges/shims) under the rib as it's bent in, can get this accomplished and use the eyeball method, for the amount of additional bend you might need. On repairs and restorations like this, I usually make adjustable bending jigs, so I can bend them on a bench, rather than fight with them in the boat. This insures I get accurate bends, including spring back and of course makes laminating much easier.

 

Lastly, these puppies are notorious for "tension cracks" in the aft sections of the bilge turn. I almost always laminate these, to avoid them in the future. Contrary to popular opinion, all the oaks epoxy well, once you remove the tannins with a chemical scrub, just prior to applying goo.

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Thanks for more tips, I need everything I can get. I was wrong on the thickness of the ribs, they are 5/16ths not 7/16ths. Hope this helps me out a bit. Got everything ready this morning to turn it over and start this adventure Monday. Par I the new ribs have very straight grain, but I cut these out about four years ago and they are very dry I'm sure.

 

Scott

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I typically use the sheer clamp (what I think you're calling the inner sheer) to hold the replacement ribs as inserted. I do often loosen up the sheer clamp fasteners to provide some gap, so I'm not fighting with them and enough space to over bend them slightly, to counteract spring back. It's not necessary and I know several that remove it and just clamp the ribs in place instead. In the end, I think you'll have to decide how much shape are you going to lose by its removal.

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  • 2 weeks later...

Got some strips soaking in a tube yesterday. Got the steam box pretty much finished also. Now if I could just get some weather warm enough the steam doesn't freeze in the air. Looks like Monday it will get up to 40 around here after two weeks of teens for highs and singles for lows.

So the plan is to give this a try on Monday sometime.

PAR the end grain in the cut strips are flat, hope this is good. If not, going to try them anyway and see what happens. My old Sony cam uses a 3 1/2 disc and just wont show something that close and detailed. Some will find it hard to believe that someone still has a:o 3 1/2 inch floppy on their pc, but I do, also I still use a flip phone. :)

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