engine and boiler stringers

[johnp]

It's almost time to start work on the boat, it's a fiberglass lifeboat hull with floor stringers already in. i was thinking of putting the wood engine and boiler stringers in and glassing over them. But, that sounds complicated, i'm not to good with fiberglass, so i was thinking why don't i just six/10 expoxy some pressure treated stingers in and put carrige bolt from the bottom of the hull up through the stingers. Then i can build up the floor stringer so all is level and put the decking on.

any thought as to why i can't do this.

John

[barts]

Any water leakage past carriage bolts will rot out stringers...

Epoxy & wood are strong and easy to do.... avoid as many holes in the hull as possible.

- Bart

[johnp]

Then it would be ok to just epoxy? no fiberglass? How few lag bolts where I notch out the engine and boiler stringers screwed down into the floor stringers?

[fredrosse]

There has already been somewhat lengthy discussions of the options for engine/boiler mounting stringers, look up the previous post subjects:

"Stringers (engine bearers)" and also "Engine/Boiler Recommendation" both have inputs and suggestions from several experienced steamboat builders.

The attached picture is an engine room section from a WWI USA wooden freighter, 282 feet long, with several 14 inch x 14 inch wood engine bearers shown.

[johnp]

Did a search on the topic and didn't find too much about only gluing down the stringers. Can anyone shine some light on this? is the epoxy enough or do i need to bolt through the hull, or lag down into the floor stringer? appreciate the help.

Thanks
John

[mtnman]

I see no reason why epoxy wouldn't be enough. I'd clean the area real good, scuff it up with a hand grinder clean again and mix the epoxy. Lag screws under the water line is just asking for trouble. If there's a stringer next to an exsisting one then glue to it also. As to protection, good paint should be plenty. It doesn't take much to hold a 2hp engine.

[fredrosse]

To add a bit to mtnman's good comments, roughing up the bond area is important, and adding a filler to the exoxy mix will make it much stronger. The filler can be wood flour(good), cabosil (better) or fine chopped fiberglass (best) for strength. The sidewheeler Margaret S was put together with a coat of brushed-on epoxy, followed by epoxy thickened with wood flour, mixed to the consistancy of peanut butter, so it can be used as a paste. Any of these fillers make a very strong paste, but epoxy alone will often run out of a joint. Look at Radow's pictures of epoxy-paste mixture putting his hull together.

[Lopez Mike]

The trick I use to mix up epoxy with a filler the way Fred recommends is to keep adding filler a bit at a time until it will hang on your mixing stick like mayonnaise rather than like peanut butter. No oozing off however slowly. The technical term for this state is Thixotropic. This is covered in the instructions from West Systems and others. It works well and means that the gunk won't droop out of the joint and leave a void.

Another thing that is just for looks is to first run a rounded end mixing stick along the joint. And then, after it is starting to set a bit, use your finger (with a glove!) and smooth the resulting fillet.

In the case of a timber that is a little taller than usual, like one more than say three times its height relative to its width at the base, is to lay in a couple of strips of fiberglass cloth along the joint. First a narrow one and then getting wider. This makes an attachment that is essentially part of the boat hull.