Stringers Hollow?

[Bill1565]

My engine knock is back. Got pretty quiet with new rear motor mounts, larger, longer lag bolts all around. Lot of ICW motoring this cruise. Anchored early today, got out the wrenches and lag bolts were not real tight. Just for the heck of it, I tapped on the stringers. 3-4 inches wide by 8+ inches tall. Fiberglass cloth, some exrta resin slopped on top and upper sides. Sound hollow. Sounds like 2x4 over void. Longer lag bolts a waste of time if it is true. Top of list so far is new front motor mounts, new larger lag bolts, git rot or Smiths penetrating resin, and hole saw into side of stringer to see what is inside.

Anybody out there ever cut into their stringers??

 

[Ed Schenck]

Can't help Bill. But your question will force me to check the lag bolts next time on the boat. My 3YM30 is so smooth that I have not had the worry til now. It would be nice to know just how those rails look under that fiberglass.

 

[rardiH36]

I don't really know the answer for your specific boat, but here's a link to a thread about engine motor mount bolts that won't tighten. Might help. My guess is that inside the stringer is wood that no longer will grip the bolt thread due to age and maybe oil/water damage. It's hard to imagine that a designer would make a hollow stringer and expect that engine mount bolts would hold against all the stress and vibration in only 1/4" - 1/2" of brittle fiberglass.

http://forums.hunter.sailboatowners.com/showthread.php?p=762841&highlight=bolts#post762841

 

[Bill1565]

Thanks rardi. We are on Cellphone internet access and didn't do our own search. Will investigate what is actually under the fiberglass when we get home.

 

[David in Sandusky]

It's worth a look under the glass of the stringers. I knew of one case where the wood on a couple of stringers was completely gone or rotted. (On a Junneau 32, but I think the problem was more about a PO leaving the boat with a foot of water in the cabin.)

 

[Ed Schenck]

Never had a "knocking" sound. Seems like it would have to be the shaft on the stern tube to actually make a noise like that. Loose mounts would certainly allow that.