motor mounts and stringers

[salty87]

my motor mounts aren't so straight forward...for a 454 which causes the mounts to be a little wider and more substantial than similar models with 351's that i've seen.

the old wood was so mushy i couldn't tell what was going on...it had already went, haha. the old inner stringers seemed to have the motor mounts notched into them. the old motor mounts were something like 5" wide and 5" tall and sat on the outside of the stringer.

should those stringers run continuous (3/4" x 2 for the inner stringers) with the motor mount area's added to them or should i somehow tab the stringers and mounts together?...make sense?...pic...this overhead gives a good view. maybe 1 1/2 of ply plus some 4" PT lumber to build it up?

overhead

this is closer, you can see how the exhaust pipes poke out from under the deck

 

[qaztwo]

Re: motor mounts and stringers

have you own this boat since new. looks like the fiberglass has been cut out for the engine mounts. On the right side looks like theres a hollow spot compared to the other side. Is the engine stringer wood solid or is it a skeleton for the fiberglass.

 

[salty87]

Re: motor mounts and stringers

no, i've only had it since 2000. looks like someone had been under the deck before.

the engine mounts were only held by the fiberglass shell. most of them just pulled loose with the engine, i think 1 had to be unscrewed from the stringer. some of the mushy wood stuck to the threads of the bolts leaving the puddles.

i think i'm going to run the stringers through there as continuous as best and add wood to make the mounts wider. glass it all in.

 

[oops!]

Re: motor mounts and stringers

when someone eles goes in and doesnt do it right..it can cause a lot of trouble....

man that looks like a lot of work.

im not framillar with mid engine designs.

but i would think mounts on wood blocks glassed to the stringers..

can you get diagrams from the mannufacturer?

good luck bud

oops

 

[qaztwo]

Re: motor mounts and stringers

I have seen the exhaust ran next to the prop shaft and have seen them tuck back into the boat. If there are no patch jobs in the stern for the routing of the exhaust I would say everything is stock except for the lowering of the engine mounts. If you wanted to run the stringer all the way back would have to move the exhaust inward. My guess is that in order to use the 454 and keep the angle correct the mounts had to be lowered. My only qustion is what are the motot mounts bolted to. Do you have the engine and trans?

 

[salty87]

Re: motor mounts and stringers

i think the mounts are the original design. the mounts (1 is still attached in the 2nd pic) were screwed into the top of the 'stringer' and the side too. i was guessing the engine was dropped lower to keep engine from sticking up too high.

i don't have any concerns about the previous design being good, just the best way to re-create it. i'm liking the idea of using PT lumber as opposed to building it up with plywood.

 

[tashasdaddy]

Re: motor mounts and stringers

the chemicals in the pt lumber will eat you mounting bolts. you will be right back where you are.

 

[qaztwo]

Re: motor mounts and stringers

I can not see how far down the mounts have been dropped. I do not know what the min distance a lag bolt needs to be placed to secure an engine. I would want at least 3inchs to drive the lag bolts down. If you simply want to redo the engine bay, measure where everything is off of a fixed point, or mark the floor where you want the new mounts to go, cut out old, transfer the measurements to the ply, notch out for the engine mounts, laminate some ply together, glue down to hull, cover with fiberglass. I would use marine ply and encap it with resin, including bolt holes.

good luck

 

[salty87]

Re: motor mounts and stringers

the chemicals in the pt lumber will eat you mounting bolts. you will be right back where you are.

i've been kicking around the idea of thickening up some poly to fill-in the sections where the bolts will go, maybe even seacast or marine tex. i'd prefer to keep the bolts out of the wood. the way these mounts will get glassed back together, they create little compartments that trap in any moisture. if the bolts aren't in the wood, i think i'll be better off.

 

[Coors]

Re: motor mounts and stringers

When i just replaced my stringers/mounts, I used a fir glulam beam, like what goes over your garage door opening. (they usually cut a foot or so off, when building a house, and toss it away-free!). Dense fir is somewhat water-resistant- not a lot.
Then, after drilling, and installing lags, removed them, and poured in some thinned slow set epoxy. Let it soak in for 2 hours, then removed the excess, let it cure and smeared the lags with 4200 before re-installing them.
I'll see if it works, but sounded good.