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Rebuilding Islander Transoms. This will be in 2 posts in this thread.


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I started my transom "rebuilding career" on an 18 foot Sylvan and ever since, whenever I bought another boat to "upgrade" I replaced the transom, mostly because they were rotten .

So I will start with how to check a transom when buying a boat. Often the seller has no idea that his transom is rotten so do not count on info there. Take a sharp pointy knife, crawl into the stern as much as you can and stick the pointy object into the transom where you can, and not just near the bottom. Check if the transom is fiberglass covered, because that would hide,but not prevent wood rot and that cover has been put on to hide something. If the knife does not penetrate anywhere or it is very hard to do so, you are alright and there is no need for replacement. If it is soft, it is time to replace.

It is a good idea to start with taking pictures at every step of the process  and writing comment with the pics.

Before you replace your transom you will have to pull your engine and separate the outdrive from the transom and of course whatever else is connected to the transom on the inside. While doing that you should think about what you can disconnect from the engine (gear shift cable) and slide out with the outer drive housing through the transit hole. You can either remove the engine from the boat (preferred) or lay down a piece of plywood  farther forward on the boat floor and put the engine there.

Now comes the transom cover. It is held in place by rivets, bolts ( the bolts have nuts,save bolts and nuts) and screws which are under the black rubber bumper strip on the back and sides, and a wood frame farther forward, this wood frame is often quite as rotten as the transom. Take pictures and measurements in order to remember where it is connected to the alumium on the side. After you remove all the fasteners the cover should come loose and you can remove it. Now take off whatever is connected to the inside. next, remove every last screw and bolt on the outside.Next, measure the length of the transom It is usually smaller than the stern. This is also a good time to check the foam for water.At least in the 22 footer it is possible to unscrew the aluminum sides holding the foam. Just remove them and you will have a good viev of the foam from top to bottom. Remember, every cubic foot of saturated foam weighs 68 pounds,4 or 5 feet means an extra 300 pounds to push  Removing that aluminum will also make it easier to remove the transom. Try to remove the transom while pulling from two points in order to prevent binding, also try to pull under the angle that the transom is in and not just straight up. You will find that the transom is under the aluminum cover on the sides,so just remove the bolts holding the sides  about a foot length and you can just bend those sides up. it is easily bendable.

Next is removal. The transom is about 8 feet wide and at its deepest about 40 inches. This may be too long for a cherry picker. Try and remove in one piece if not go piecemeal.

My next post will deal with measuring a transom.

Edited by rolmops
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2 hours ago, woody 184 said:

How much does a transom cost

It can be as much or as little as you want.

If your boat lays in the water from May until October you probably want the marine grade or Douglas fir plywood. Marine grade will cost you a lot of money. Add to that the 2 component epoxy paint and you will end up with around $500 give or take.

If your boat is a "trailer queen" and out of the water most of the time you can make do with cheaper plywood and deck paint. That will cost you around $200 or less. but the transom will still last you 20 years.

In both cases you will have to buy a seal that sits between the out drive and the transom. I don't know what those do currently cost

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Measuring the transom  before cutting the plywood into shape.

If you were lucky enough to be able to pull the transom out in one piece, you  simply lay it on your plywood, and draw its shape onto the plywood.

If it came out in pieces , you can just take a note book write down the length of the stern and measure at a 90 degree angle down to the the bottom of the stern ( on the inside)every 5 inches and write the numbers down until you are at the other end of the transom. Next, you draw a line on your plywood and mark the length of your transom on it. Now you draw a straight line at 90 degrees every 5 inches along the transom length line and make an x at the downward line using your measurements. Now connect the x dots and there is the shape of your transom..Next,you cut it out and put it in the boat to make sure it fits. Make sure that you have half an inch free  on the side and about an inch and a half above the drain plug. (so the bottom of  your transom will not sit in the water all the time). Make sure it sits correct and fasten it to the stern with a few screws( top sides and bottom) so it sits snug at the transom. now you can draw the shape of the outdrive center hole  onto your plywood by tracing the hole in the aluminum transom.

Next you can remove the plywood, put it on the second board, trace its shape and cut the second piece out. Having done that, glue the 2 pieces together. I Like gorilla glue, but you should use what you like as long as it is water proof glue. Next it is time to paint. Use a paint that penetrates the wood and is water proof. Don't paint the side that the drawings for the center hole are on just yet but only after you have cut out all the parts that you marked. You can cut the center hole either before or after the painting. Next just lower your new transom into its place and bolt it onto the aluminum.When you drill the bolt holes make sure to use a gadget on your drill that sets the drill at a 90 degree angle off the transom. Seal every bolt hole with M5200 so there will be no water seeping in through the boltholes. Oh, don't forget to put that 1/2 inch thick center hole shaped piece of wood on.

That is all there is to it.

Edited by rolmops
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