Transom Replacement

[stringtyer]

I found (and consequently stole - price wise, that is) a nice MonArk 1448 Jon. The boat is in great condition except for the plywood transom panel. I need to replace it but can't figure out how to do that without removing and replacing a bunch of rivets. I'm looking for some advice here since I have exactly NO experience with standard rivets.

Here's the problem. In the attached picture (I hope this works), the arrow on the left points to a sheet aluminum "L" bracket that holds the transom in place. There is another on the starboard side of the boat. The arrow in the middle points to one of the 10 rivets in the brace from the deck of the boat to the transom. The question is; is there any way other than removing all those rivets (18 of 'em) to replace the board? Since I can guess the answer, the better question is, how do you go about (a) removing the old rivets, and (b) bucking the new ones in place?

Any help will be appreciated. I'll be starting either a thread on this site or a blog about the mods for this boat.

Thanks

 

[acabtp]

you should be able to remove the metal trim on top of the transom and then slide the old transom wood out the top without removing the knee brace or side bracket that you are pointing to

 

[stringtyer]

This boat has the cap to the transom formed into the transom itself so it can't be removed. In other words, it is part of the transom. I checked with a neighbor who has an air impact wrench so I'm going to mod the end of one of the punches like someone else on this site has done. Now, I gotta' get up the nerve to drill out the old rivets. I hate the idea of making holes in the boat ... even if they are already there.

 

[lckstckn2smknbrls]

Removing all those rivets is the last way to do this. I removed the corner brackets and straightened the top cap to replace my transom. Then I bent the cap back in place. You could cut the cap off with an angle grinder and fabricate a new one.

 

[stringtyer]

OK, it's been right at 6 months since I had a chance to play with my boat (that teaching job gets in the way) and I am back at it. I backed the boat into the garage today and ground/drilled out the rivets holding everything in place. Got the transom out and cleaned up the crud on the aluminum stern.

I'll be cutting the new transom on Wednesday and have some questions y'all may be able to help with. First, it looks like the total transom thickness should be right at 1". I have plenty of good 3/4" ply and am thinking of laminating a 1/4" piece at the top where the motor mounts. Any other suggestions will be appreciated.

Also, I am thinking about sealing the edges/faces with several coats of polyurethane or spar poly. The question is this, should I fiberglass the edges/faces or is that simply overkill?

Any help/suggestions are welcomed.

 

[lckstckn2smknbrls]

I'd do the 1/4" layer over the whole transom otherwise the transom won't be thick enough where the knee brace and the L's on the sides are and will be 25% weaker.
I see no need to fiberglass the edges.

 

[JMichael]

Instead adding the ¼" to just the top edge, add it to the entire ¾" piece. It will make the transom stiffer/stronger and you'll need that full thickness at the knee brace for proper fit. I would not use poly at all. Fiberglass resin would be great to seal the wood but if you need more working time use spar varnish. Varnish has a harder finish and will hold up better than polyurethane.

 

[JMichael]

Well as usual, I'm a day late or a dollar short and somebody beat me to the post. Pretty much duplicate answers with the exception of the opinions on fiberglass resin though. :lol:

 

[Captain Ahab]

No need to fiberglass (and I would suggest you do not - acts as a great moisture trap unless done correctly and sealed)


I do suggest using a 2 part epoxy marine sealer - I used Overtons and it worked great and was simple to do

 

[lckstckn2smknbrls]

What glue are you planning on using? I recommend Tite Bond III or Gorilla glue.

 

[stringtyer]

What glue are you planning on using? I recommend Tite Bond III or Gorilla glue.

I'll definitely be using Gorilla glue. It is a bit of a mess to deal with initially but I know it will hold forever.

I'll post some pix as I fab and install the new transom.

Thanks for all the help.

 

[BigTerp]

I haven't worked on my boat since probably September. Been using it to duck/goose hunt. But the first thing I did when I got mine was to replace the transom. It ended up being alot more work than I thought it would be, but well worth the effort. Take a look at my thread in my sig and it might give you some help or ideas.

 

[stringtyer]

Lots of good information in your posts. I've got the plywood and will take it to school tomorrow and fab it in the wood shop.

I understand the reasons for using plywood and will be doing that but wonder about the possibility of using a solid transom. I have some beautiful quarter-sewn white oak that I thought about fabricating into a transom. I thought I would mill some 1" thicknesses and glue them up using two or three cross braces dado cut into the back at half depth. I'd like your opinions/experiences with solid wood for a transom. In the meanwhile ... plywood it is.

 

[stringtyer]

It has been some time since I last posted about this topic. Since I am not teaching this summer, I finally have time to work on my boat and the first project has been to replace a rotten transom. I took everyone's advice and glued up two pieces of 1/2" plywood, cut it to match the old transom, and coated it with four coats of Minwax Spar Urethane. Installed in the boat and looks great.

Next project ... rebuilding a 1969 20-HP Johnson that a friend of my son-in-law gave me. I'll post details about that as it progresses.

 

[stringtyer]

OK, that post was a bit screwed up. Someday soon, I'll learn how to post pictures correctly.