Stringer Integrity

How do you know when your stringers are going bad? I am starting to question the integrity of mine. They seem pretty solid but I have noticed that the hull and topsides seem to be weakening (vibrating) when under acceleration or chop. The motor has a lot of torque but I still think something's not right.
Any thoughts ???

You'll know when there bad, the best place to look is near the motor mounts, do what todicas said, where you dont see wood use a ball peen hammer and tap, If you have bad spots you'll here it with the multi purpose hammer

Unexplained vibration is a very good indication that not only the stringers are bad but also they are either separating from the hull or the floor is separating from the hull as well. If there are bolts attached to wood that you can turn but not tighten then the wood in that area is rotten. If you notice cracks where the stringers attach to the hull the stringers are likely wet in that area. You can test by banging the handle of large screwdriver against the stringer. If it seems soft then poke an ice pick in that area. If the pick goes through then there may be rotten wood. Of course there is always when you can actually see the rotten wood and/or mushrooms.

I stumbled across this while trying to find out what type of mystery boat Hollywood posted on another thread. Hope it helps........

1. Does the floor sink in when you stand on it. It can be very solid in one area and mushy in another.

2. Open engine cover and try to tighten the main lag boats that go in the stringers. If they don't tighten or spin freely,you could have a problem.

3.   Pop up the floor behind the engine cover, it is one piece of plywood that covers the drive shaft. There you can examine the stringers as they run to the back. They should be fibergla$$ed, but sometimes the fibergla$$es has chipped off and you can see the raw stringers.

4. Also you can run the boat over a scale and then compare with the weight published in the ski nautique manual. Water in the foam and stringers will add quite a bit of weight to the boat.

5. Get to a stringer and use a hydrometer to measure the level of humidity in the wood.

If they are rotten, they can be replaced, but realize that it takes a lot of time. However, once you do get them replace you will have a very solid boat for a long time.

The places that rot the first are behind the drivers seat and in front of the observers seat.

Many thanks to all who posted on this thread. After reading all your comments I think mine are in pretty good shape. The boat is a 1967 Wildcat, not quite the same construction as the nautique's but similar. I did spin a couple of the bolts when I replaced the engine/gear a few years ago but I poked around with a pick and found solid material. I recall putting 5200 in the holes. I will be pulling the floor soon to replace the exhaust hoses so I was thinking of doing the stringers at the same time. Thanks again.

Dale

Larry

This boat lives up North and I'm lucky enough to have a garage to keep it in. When I dig into it I will bring it south. I appreciate the offer. Are you doing the Boston Show? And have you checked out the NE reunion thread? I'm about to post on it.

Dale