Stringer Repair

[Steve Hornsby]

Hi all,

Concerning my ROSARON project - posted 09-16-2004.

I have to replace my stringers, but have a few concerns that are holding me up. After I removed the engine and all hardware, I ran string lines from each end of the stringers. They are 14ft long. The oil soaked stringers deflect (downward) about 1/2 to 3/4 in the middle.

If I apply a little pressure to the bottom with a jack, I can take out most of the deflection, but I was also putting some rise in the sheer. Before I knew that the stringers were bad in a few spots and made the decision to change them out, I would have probably left all as is since the hull shape looks about right. ROSARON has a bit of a rounded hull profile anyways - the sheer is straight with a gentle fall towards the stern.

Questions:

1. Novice question here - are stringers usually put in the boat to be flat along the top? - would absolutely make sense. Should I aim to take this (or some) deflection out if it doesn't affect the sheer too badly?

2. I am thinking of laminated fir replacement - is this better than solid lumber - looking at 8/4 by 7 inch (at the thickest) by 14ft. They are planed on the bottom to mate with the hull profile. Probably more wasted woood if I went with solid lumber.

3. They seem to be attached thru the bottom of the ribs. How does one attach replacements - plank off, screwed thru ribs? Is there another way?

I realize that the first question my be hard to answer from a far, but any thoughts will help the process.

I am trying to find someone who could provide another set of eyes and opinion, but I'm not having much luck in that area. She's a 1942 and a one-off. Remnants of the company exist but help has not be forthcoming - and in fairness her builders have passed on. I live just north of Kingston, Ontario.

Thanks Steve

[Bob Perkins]

From my own experience, I can say that the motor stringers should be flat on top over their length.

I had to make a pair of 5" x 1 1/2" x 17' stringers. I first make two 5" x 3/4" 17' boards using scarph joints, then glued the two halves together..Make sure you have a long flat surface to clamp against.

The result is a very strong and stable beam.. They have not moved (in any direction) a bit..

If it were me - I'd try to restore the boat shape with straight ones - but I don't know if that is proper in your case. Reattach the same way the old ones come out....

Hope this helps,
Bob

[Mike Vogdes]

Do you have a reliable water line you could use as a reference point for maintaining the hull shape?

I would think the best way to refasten the new stringer would be as you say, remove a few planks and rebolt thru the frames.

[Steve Hornsby]

Thanks Mike and Bob for your thoughts. Both were helpful.

I have applied a bit more pressure directly below the stringers and taken a bit o'pressure off the keel at that point. I think I'm getting to a happy medium and better shape.

I am now guessing that the boat was stored with too little support under the stringers at the engine and with too much reliance on the keel to take the load.

Thanks again