22' Marlin Chinook Transom rebuild

[wiltop]

After weeks of contemplating and getting conident by the day after reading everyone's threads I finally started the transom project on my 22' Marlin Chinook today.

After removing the engine, transom bracket it was finally ready for me to cut the cap off and take a look at the damage.


Got the bracket off, remove the trim tabs and cut the cap off the back. If you notice I didn't cut the cap around the corner, I wanted to be sure that the transom outer glass don't stretch too much.

As you can see the cracks along the top of the transom, it is crack all the way across the top.

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

View attachment 102193View attachment 102192Here's more pics of the rotted transom
View attachment 102191

This is some really nasty stuff.

View attachment 102194

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

Here's some pics of the floor cut out, look at the foam under the port and starboard aft deck. Does anyone have any quick remedies to get all that foam out?
View attachment 102195

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild



Sorry re-inserting pics, got this tip from woodonboats.

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

I got some questions, the floor is 3/4" Mahogony plywood, does anyone here agree with this stuff on the transom? The floor is covered with this stuff, really heavy wood but ver solid. Take a look at the thickness, kind of overkill. I got a couple of different opinions from local repair shops, one said that it doesn't soak up Polyester resin very well the other said it does, does anyone have any recommendations on the replacement wood?

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

Has anyone used mahogony for their transom? I went to Home Depot yesterday and their Marine ply looked nasty, lot of voids and their not very straight, the local boat shop is out and all the other lumber stores are out as well.

 

[Woodonglass]

Re: 22' Marlin Chinook Transom rebuild

wiltop,

Your boat appears to me to have been and Inboard/Outboard that was converted to an Outboard using what I call a "Pod" to mount the Outboard. the transom "HOLE" for the outdrive has been filled in. The STRESS that the POD put on the Transom has caused it to fail. This is typical for this type of Installation especially when there are no Transom bracing installed to aid in taking on the additional stress put on the transom by the POD. In my opinion you will NEED to install these barces to ensure that this problem does not reoccur in the future. You should also BEEF UP the transoms thickness and Additional tabbing into the hull would be a good idea too!!! See if Lowes or Home Depot carrie Flooring Underlayment or Arauco Plywood. Either of these would be good choices for your Transom wood. How thick is the existing transom??

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

You are correct, it used to be an I/O converted over to an outboard. The original thickness was 1-1/2", I am thinking about the braces and am planning for that right now. I will check HD (No Lowe's in Guam, yet) or other local lumber yards to see what they have. Other than the braces, what transom thickness do you recommend?

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

I also forgot to mention that the total transom thickness is 2" with the outer and innerskin, the 1-1/2" was just the wood. Also when I purchased the bracket from D&D Marine, it came with a aluminum "C" channel that bolts to the inner side of the transom. After the rebuild, I'm going to also intall a 1/4" aluminum diamond tread plate (along with the channel) on the inner skin so that the force of the motor is spread out evenly across the transom.

 

[Woodonglass]

Re: 22' Marlin Chinook Transom rebuild

If she were MINE, I'd do it like this. When the deck is out, I'd tie in three knee braces to the stringers as in the drawing below. I'd make the transom 2 1/2" thick. I'd use EPOXY to laminate the epoxy (IT's stonger than Poly) I'd use 3 layers of17 oz mat to tab the tansom to the hull. First tab of 6", second 9" and last of 12". I would also consider making Corner Gussets for the transom as well. There is a tremendous amount of stress on the transom due to the "POD" and you need to reinforce it in any way possible.

(Click the pic to Enlarge)

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

Ok, I'll take that into consideration on the rebuild. That is better than adding and additional 70# plus pounds of aluminum plating on both sides.

 

[Woodonglass]

Re: 22' Marlin Chinook Transom rebuild

The aluminum will add MINIMUM strength to the transom. It must be tied to the hull for you to gain any benefit.

 

[wiltop]

Re: 22' Marlin Chinook Transom rebuild

Thank you sir, got some extra help this weekend. Going to complete the tear down and grinding, if the weather holds up. We have a Typhoon north of us bringing a lot of rain our way.

Also since I'm going to cut part of the stringer off, I was thinking of encompassing the brace and the stringer as one piece and have a couple other braces along with the corner gussets.

 

[Woodonglass]

Re: 22' Marlin Chinook Transom rebuild

Now you're talkin!!!!