Transom plywood is rotten, on inboard mercruiser 1990 thompson cutlass 190

[Woodonglass]

If you're foaming the hull, and since the seats are boxed, a 1/2" glassed deck should be adequate in this case, in my opinion. If you're not foaming then 5/8" would be better. We're talking about 8 lbs per sheet difference.


Plywood Thickness and Weights:

Sanded Nominal Thickness
1/4 3/8 1/2 5/8 3/4 1-1/8

Actual Thickness
1/4 11/32 15/32 19/32 23/32 1-1/8

Approximate weight in lbs. per 4x8 sheet
22.0 28.5 40.6 48 60.8 84.5

 

[ChizelSpiel7]

No Title

Haven't touched the boat in a week now. want to finish the grinding for the transom and the floor this coming week. Few questions with pics and video.

Video:http://youtu.be/VYFrNa2KCOY

 

[ChizelSpiel7]

S.0.S, can anyone advise me on the pictures/video with questions on them, on post #82.. Thanks in advance!

 

[JASinIL2006]

i couldn't watch the video, and I was having a tough time reading the tiny print on the photos you posted, but here goes... In the second photo, you want to know if you should keep the lip where the deck attached to the hull, yes? As long as you have measurements to allow you to get the deck level placed correctly, I'd want to grind off that lip. I think the lip will just make it harder to tab the dech to the hull. I think a smooth hull would be easier surface on which to get a clean and strong bond.

Sorry, I could not really make out the first pic and text too well on my iPad.

 

[WOEISMEIGOTTA470]

I agree with the above post, and would say yes to both questions posed in your 1st photo. You want to grind down the lip flush to the hull, and use hairy PB to fill in the uneven areas around the transom. You will be using PB to fill in all the gaps between the new wood you put in place anyways if that answers your question.

 

[ChizelSpiel7]

Thanks!!

 

[WOEISMEIGOTTA470]

No Title

I know that on these boats they only have two main stringers down the length of the hull. So just another tip on what I did to keep the new floor level and set to proper height along the edges...see attached.

 

[JASinIL2006]

Mine only had the two stringers too. I didn't glue blocks to the hull.... I didn't want to take a chance at creating any hardpoints. I left a gap (1/4" or a bit more) at the place where the deck met the hull. I then filled the gap with thickened resin and then tabbed the deck to the hull per Woodonglass' excellent instructions.

 

[ChizelSpiel7]

I know that on these boats they only have two main stringers down the length of the hull. So just another tip on what I did to keep the new floor level and set to proper height along the edges...see attached.

I like that idea! I could leave that lip that is there already, that would help keep the rigidity. Then just lay the new boards over the blocks you are describing and screw into blocks and tab to the existing lip.

 

[Woodonglass]

That'll work great, just make sure to run your tabbing up the side of the hull too!!!

 

[WOEISMEIGOTTA470]

...I didn't glue blocks to the hull.... I didn't want to take a chance at creating any hardpoints.

I hear what you're sayin', but where those blocks are located, they are tucked into the corner and the glass is laid up real thick in the corners of the hull, so shouldn't need to worry about hard points in those areas. I only used a small few, basically just as a temporary means of supporting the deck until it was tabbed.

 

[ChizelSpiel7]

I'm back. I got burnt out working on this thing. I am going to start working on it again. Gonna try and get this boat working by summertime. Hopefully i can get it done this time.

 

[jbcurt00]

That 'skinny little stringer' is the keel and if it too is rotten, its got to come out and be redone as well

 

[ChizelSpiel7]

Still have not done anything to this darn boat since last post. But now that i have been layed off after ten years at this company. I may have at least 6 months unemployment. I am certainly going to try and enjoy a little time off before i look for another job. Although the unemployment office has this new program that makes you go into office every week, to get you a job as soon as possible. Gonna try and hold out from gettting a job, and back to the real world till november if i can help it. So here i go again. Gonna try and get off my lazy arse and put some time into this transom. I guess the first order of business is making a template of the middle section of the transom. Then by some 3/4 x2 marine of arauco wood. Then the real work begins.cutting,Mixing resins,making peanut butter, tabbing. Thats what I really am intimidated of doing. But, hopefully you guys have not given up on me yet.

 

[ChizelSpiel7]

The fiberglass is about 3/16". With 2 plys of wood im shooting for 2". Should i buy 1 sheet of 1" and second sheet 3/4" for a total thickness of 1.937" plus resin and fiberglass?

 

[Woodonglass]

Your Transom has to be 2" - 2 1/4" to conform with Mercruiser specs. 2 pieces of 3/4" with a 1/2" piece sandwiched between. It'll be just about 1 15/16" and then when you laminated it with the resin and glass it'll be just about perfect.

 

[ChizelSpiel7]

Made the template today.

 

[ChizelSpiel7]

Made the template today. Thanks woodonglass. Happy you are still here to help!