Glass I/O motor mount replacement

[putback]

This is an '85 Starcraft 191 I/O. Stringers, transom, bulkheads, deck all fine. Motor mount area needs replacement. I've done some glass work but never structural, need some advice. I've read some threads and come up with his. Cut out the wood/glass that's bad, prep area, set the wood with the pb mix and re-glass as original. 1st what do you call the 2 rectangle boxes along the stringers glassed to the transom, stringer, hull and bulkhead? The uprights are 1 1/2 X 4" fir, the tops are 1 1/2" ply wood. Is that the right wood for the rebuild? 2nd, what would be the proper mat and resin to use in this area? Have'nt found a thread specific to this spot on the hull.

 

[Woodonglass]

Those are your Motor mounts. Since they are Hollow boxes, I'd assume your motor was mounted with studs sticking up thru the tops of the boxes?? Is that so?? Keep searching there are Lots of threads where these have been restored. What have you done to ensure that the transom and the stringers are structurally sound? Have you drilled and core sampled them. Personally I'd use 3/4" Ext. Grade Plywood and laminate enuf of it to get the size needed, and make em Solid so you could mount the motor using Lag bolts. I'd then re-glass it back into the boat using Polyester resin and 4 layers fully wrapped of 1708 biaxial fabric. You need the bulk in the motor mounts to carry the load of the motor.
This might be of some interest..
http://forums.iboats.com/forum/boat-...or-a-4-3l-merc

 

[Bondo]

Those are your Motor mounts. Since they are Hollow boxes, I'd assume your motor was mounted with studs sticking up thru the tops of the boxes??

Ayuh,.... The motor mount is the flat board, forward center, with the 2 holes in it, it's an in-line motor, not a V-motor,....

I'd recommend gettin' a chunk of white oak, 'n glassin' it in there,....
That'll hold the lag bolts well,....

 

[putback]

Yep its a MR140 power train and attached with lag screws as Bondo discribed. The picture shows how far I cut in to the mount pad to find solid wood, near halfway. Woodon, I've read a # of your post and learned. The stringers I could get to through the ski locker, fuel tank bay and motor area. Once the boxes were opened up in the engine bay the stringers are exposed. Port side is opened up a bit but the exhaust pipe hides it in the pic. A little damp near the stern but solid.In the transom I bored 6 test holes. 2 each, near bottom, midway & top plus the keyhole is now exposed, all solid and dry. Bulkheads fore & aft the fuel tank bay good as new. Bottom line, the only faults I can find with this boat are the wood rot in the picture, some interior & paint. I bought the boat as a donor. It came with N I B seats and 3 gals of original colors Supermarine paint. I guess it just makes sense to re do this boat useing the above advice, unless you can think of someth ing I've missed?

 

[putback]

Thanks Woodon, that link you posted cleared up my question about the "boxes". A V engine mounts to the boxes, an inline mounts to the ctr pad. Have I got this right. Starcraft built the hull to accept either engine then had whatever power train installed?

 

[Woodonglass]

Duh, I'm not a BIG I/O guy but now I see the center mount!!! Sorry for my misleading you. Bondo set you straight and gave you great advice. White Oak, if you can find it, is a great wood to use. If not you can build the mounts back to the same dimensions using the plywood I mentioned. Predrill the holes and then coat the holes and the Lag bolts with 3M 4200 when you mount the motor again. As for those side boxes, I don't know what you call em, but I'd prolly use the same Ext. grade plywood and build em back to the same dimensions and glass em back in with 2 layers of 1708 instead of 4. If they are not load bearing then 2 layers should be enuf. But hey, like I said, I'm NOT an I/O guy so maybe you should get some advice from someone that has done one of these boats before. This is the first one I've personally seen here on the forum but maybe someone will come along with more up close and personal experience.

 

[putback]

I just went down and checked the glass I cut from the boxes, 2 layers. of mat. I'll buildum back with plywood and reglass w 3 layers just for the piece of mind. No prob on the white oak for the mount, can get 3" kiln dried locally, orig is 2 1/2" plus glass, I'll plane it. Another rookie ? Any problem mixing black color into the resin, it would make a neater looking job matching the rest.

 

[Woodonglass]

You can use coloring but most just use bilgekote or Gel Coat after the glassing work is done.