Transom rebuild for my new Mud motor

[pappy8745]

Hope you all can help me out here. Fairly new to boat ownership...I am switching my outboard over to a mud motor. I have a Jon boat, it is a 16x52 and it appears it was cut down to be a short transom at some time. First of all, I need it to be a tall transom and secondly I need to beef it up quite a bit. My mud motor is a 27hp Kohler Prodrive. Will put out quite a bit of torque. I also obviously need to replace some of the wood in the transom also.

So: What metal/thickness should I use to build up the transom and what design would be best?

Any other tips/ideas would be appreciated.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

any ideas?

 

[tschmidty]

Re: Transom rebuild for my new Mud motor

It's not the metal that will give you the strength, it's the inch and a half of wood behind it. You need to get that old wood out and make a good wood transom, typically 2 layers of 3/4 inch plywood laminated together and a layer of epoxy or resin and a layer or two of glass (all just to waterproof). For metal I would try to patch that hole with a sheet of aluminum, probably 1/8 inch thick to give it a little strength.

 

[Bob_VT]

Re: Transom rebuild for my new Mud motor

Welcome to iboats.

This is going to take a bit of research here. What size transom height does your motor need? Does it need to be higher?

It appears as if someone cut the transom from an extra long to a regular shaft.

Get a measurement from the transom (where the motor mounts) to the bottom of the hull on the outside.

Used street signs are a great source of thick and durable aluminum. If it does need to be increased (don't do it yet until we are sure) I would strongly suggest a but of aluminum welding.

The wood that is there needs to be removed. The new transom should be at least 2 pieces of 3/4" exterior plywood that has been coated with resin (epoxy or polyester)..... but, once again the key will be the required transom height for your mud motor.

I will tell you that the mud motor will help you get through just about any condition of water so the transom will have to be real strong.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

Okay, thanks for the help so far. The transom, before it was cut out was 21 inches and that is exactly what I need for my mud motor. So I do need to fill in that entire void.

 

[osborn159]

Re: Transom rebuild for my new Mud motor

how bout a pic of the powerplant??? these guys got your headed down the right road, 3/4" 2 plys glued and sealed, old road signs, hmmm i live in the middle of nowhere there all over. little traffic, wait i have a f/g boat

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

So should I do something different with the Transom other than 1.5 " wood and regular alum. since I have to fill that big space? I was thinking I would have to put two layers or alum. there?

 

[seamorewaterVIP]

Re: Transom rebuild for my new Mud motor

So should I do something different with the Transom other than 1.5 " wood and regular alum. since I have to fill that big space? I was thinking I would have to put two layers or alum. there?

nope one layer of alum guage the thickness and go to a metal working shop or supplyer and see if they have a drop piece that is big enough to complete your project may take some looking on your part. Cut the sheet to fit leave extra metal at the top have some one with a metal break break the top to match existing top rail. Then weld the piece in place. If you are not experienced in welding alum i suggest paying someone who is experienced to do it for you. It is nothing like welding steel and you have to have special equipment to do it. Then make a template for the new transom and follow the directions given above. two layes ab/bc or ext grade 3/4" ply laminated togather with poly(cheaper) or epoxy (expensive) then cover the entire surface with poly or epoxy. Dont mix and match on the reisen epoxy will stick to poly but poly won't stick to epoxy. Then cover with some type of hq marine paint to protect from UV rays. Then install in boat my .02 worth.

last suggestion if you plan to bolt transom to aluminum I would drill the holes in the wood over size fill with poly or epoxy the redrill to the correct size that will water proof the wood inside the hole . Then use 3m 4200 to seal the bolt. water intrusion is any boats worst enemy.

If you will do all this it will last a VERY long time.

You can use the search feature to look at some treads that have some simular things.

Welcome to Iboats and there is a wealth of info here Just ask and it will come.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

Awesome, thanks!

 

[seamorewaterVIP]

Re: Transom rebuild for my new Mud motor

all of the wood inside the black box is part of the transom you will need to look behind the boxes on each side to see if there is wood between them and the outer skin if there is it may need to be replaced as well for structural strength. if the boxes are alum and are rivited to the transom then don't worry about what is behind them.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

There is wood behind those boxes and they are rivoted to the sides and the bottom of the boat, so they would be very difficult to get out. SO, do you guys think just doing this "T" replacement of the transom will give me enough strength to handle my mud motor? Just making sure.

And then, should I just cut out what I can of the wood down to those boxes?

 

[seamorewaterVIP]

Re: Transom rebuild for my new Mud motor

There is wood behind those boxes and they are rivoted to the sides and the bottom of the boat, so they would be very difficult to get out. SO, do you guys think just doing this "T" replacement of the transom will give me enough strength to handle my mud motor? Just making sure.

And then, should I just cut out what I can of the wood down to those boxes?

I would think so simply due to the transom knee braces that are there but I am not a tinny expert. maby some of the starcraft guys in here can pipe up and give you some advice on that particular issue. I know that they will want to know what brand of rig it is and if the boxes where orginal, and if there is acess to the inside of the boxes any where. and of course the will always want mor pics.

the knee braces (the triangle things) have rivets that go through the transon is there wood between knee braces and the transom? if so you may need to think about some feasable way to replace all of the wood. :redface:

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

I was thinking about the access to those boxes too. One of them has a flip top, so that you can store things in there. The other one is filled with styrofoam and totally enclosed.

As for brand...I might have to look more to figure that out. I would assume the boxes are original or really well done, they are very uniform.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

Well I ended up getting into both of those boxes (one by the storage access and the other I cut a square out of the top of it for more storage eventually) SOOOOO, I have removed the entire transom and will replace the entire thing. I think after replacing the wood I will just have a metal shop do the rest for me. I will let you guys know how it turns out. Thanks for the help!

 

[seamorewaterVIP]

Re: Transom rebuild for my new Mud motor

Well I ended up getting into both of those boxes (one by the storage access and the other I cut a square out of the top of it for more storage eventually) SOOOOO, I have removed the entire transom and will replace the entire thing. I think after replacing the wood I will just have a metal shop do the rest for me. I will let you guys know how it turns out. Thanks for the help!

hey pappy take pics of your progress and post them so that we can see what you are up to, give encouragement, and make suggetions as you go.

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

Alright, here is what I have...almost done. I did replace the entire transom with 1" (the width in there befor) treated plywood epoxied and then in between the boxes I put another 1/2 in. plywood section. Then I just got it back from the welder today and he made that metal sleeve to go over the transom and I just have to drill and bolt stuff back together. It is 1/8 inch thick aluminum and the knee braces got welded in place on the back corners. So a couple rivots and bolts and I am in business. I will show you guys my motor once I get it mounted. Thanks for the help along the way!

 

[Bob_VT]

Re: Transom rebuild for my new Mud motor

Treated plywood will REACT with the aluminum hull but I guess it's too late.

You said you used epoxy on it and I hope it was a generous coating. I would use all stainless steel fastener's and be certain to coat each one with 3m 5200.

Please keep an eye on the PT wood and the aluminum..... you look like you did a nice set up.

I am looking forward to seeing that motor mounted and scooting along!

 

[pappy8745]

Re: Transom rebuild for my new Mud motor

uggghh. LOL, well I did coat the trash out of it. People were saying exterior grade and that is what I thougt I got???? What should I have used? Regular plywood?

 

[carberry]

Re: Transom rebuild for my new Mud motor

Hey,
Great job so far on the transom rebuild. I am gearing up to do a similar job on a '75 Dell Quay Dorry 13.5' (Boston Waler type hull foam core).
I had a question. Once you removed the two boxes and the old plywood, did you leave the existing exterior skin of the boat (Aluminum?) How did you fasten the new ply to the hull?
Please post more picutres if you have any more of the finished product.

 

[lckstckn2smknbrls]

Re: Transom rebuild for my new Mud motor

I really think you should replace the pressure treated plywood with exterior grade plywood. Then shorten the new aluminum piece on the outside of the transom and have it tig welded on.