Blocking a boat for frame repair

[David McCollum]

I have a 1951 Matthews 32' Playboat. It has been out of the water for 12 years. I have replaced 13 frames on the port side, and here's how: From the inside I cut away parts of the stringers to gain access, then I removed only one frame at a time, replaced it by laminating 1/8 inch oak strips with epoxy resin, fastened the new frame, then moved on to the next one. Finally, I scarfed in new stringer sections and fastened them to the new frames. Now it seems the boat has compressed a bit in shape. I cannot fit the tanks back in from where they were removed. About an inch of space has been lost.

Did I make a colossal mistake? Recently a friend told me that when making frame repairs, none of the boat's weight should be upon the keel. I don't see how this can be avoided. He blames that for causing the boat to compress. I thought all along I was doing it the proper way, having attended the WB repair course, and read numerous books. But this is one detail which is hard to find information on, proper blocking.

[RGM]

Sounds like there was a few things done wrong. Hard telling without more information and/or pictures. How well supported was the boat along the length of it's turn of the bilge? If so, was it well supported along the turn of the bilge for the full 12 years? How about support under the horn timber and transom frame? What's the nature of the blocking under the keel for this duration? Cutting the stringers to make way for frame repairs/replacements shouldn't be done unless you've taken extra measures to replicate the shape and strength of the stringers prior to cutting them. Then you're looking at a stringer replacement job, long length not short cobbled together sections. How long are these scarfed in sections of stringers that you're talking about? How many are there? Some how I get a feeling that there are many of them. How long are the scarf joints themselves relative to the dimensions of the stringers. What method did you use to fasten the scarfs together? This "compression" that you speak of is probably the boat sagging and changing shape over time as a result of not being properly blocked from the get go. And from cutting the stringers to make way for the frame replacements. How long has it been since the tanks were pulled from the boat?

[ 06-03-2002, 05:47 PM: Message edited by: RGM ]

[Rich VanValkenburg]

I replaced 28 pairs of frames in Sonja, laminated from 1/4" White Oak to a finished size of 1"x1". I started this after being on the hard for a year, and the boat was supported with most of the weight on the keel so that any verticle supports wouldn't depress the planking and frames. If all of the weight was on the supports, something has to give, and I noticed that when I bought the boat 26 years ago. The hull was indented up to 1/2" at each support.

If you laminate a frame from a pattern taken at the indented hull, you'll have a frame with a permanent fault. Seems the best time to do it is right after a season in the water when the hull's had a chance to settle into normal shape.

Keep in mind that Sonja is a wine-glass sailboat hull, where a more flat-bottomed power boat hull might react differently to poor shoring.

Rich

[ 06-03-2002, 08:05 PM: Message edited by: Rich VanValkenburg ]

[David McCollum]

Thanks for helping, and I will try to answer as many of your questions as I can. The way the boat was supported when I started this project 12 years ago was with two keel supports, railroad ties actually, plus one support at the turn of the bilge on each side, about 6' forward of the stern. Then after I replaced the stern frames, I realized many more frames forward of the stern were rotten, so I started moving forward. When I reached the area where the supports were pushing the planking in somewhat, I asked the yard to remove the port side support, and they replaced it with two stern supports, close to the outboard ends. I pulled the tank out to gain access, removed two planks at the turn of the bilge also for access. After all 13 rotten frames were replaced and fastened, I cut new stringer sections to replace the parts I had removed. There are a total of 5 stringers inside, and these sections I replaced were about 10 feet long. The scarfs were 10:1, and fastened with bronze screws and epoxy. The tanks were pulled from the boat 7 years ago, and all of this work was completed 7 years ago. Since then it has been sitting in a shed collecting dust.