mojofilter my transom repair cost me £200 plus lifting and re fitting the engine, some stainless steel work and a new elephants trunk, the guy that did the transom is a specialist who builds fast fishers for a living and really knows his stuff, because the ply inside the transom was so rotten he was able to chisle it out from the top and epoxy in a new board, cut the holes and refit the drain trunk, he also made an epoxy cap on the top of the ply which will make it impervious to water ingress.... then it went back to my mechanic who had a stainless steel cap made to top the transom and re commissioned the engine.... the boat then went to someone else local who does tube repairs as i had a leek in the rear starboard tubed which was aggravating me .......dont be scared its not that difficult to remove and re glue the tubes back on, if you know what your doing of course, and its the best way to patch a repair from the inside.
In total its cost me about £450 which i could have reduced had i not had the tube repairs done and lifted and re fitted the engine myself, now though the transoms the strongest part of the boat.
I'd suggest before investing any money at all take a good hard look at your transom, remove an engine bolt and see what the ply inside is like, use something sharp and have a dig at it, if its soggy your'll know straight away, also worth lowering the engine, get a good hold of it and see if you can flex it up and down, if the transoms going it will wobble up and down quite easilly and your'll see the transom flex. I was lucky as i caught mine quickly, i knew i had a problem but kept ignoring it until one morning at the slipway a mate of mine spotted these nasty splits in the inside gell coat indicating a problem, that day we went to the pub instead !!
Bottom line is they can be fixed and to someone who knows what they are doing its no big deal !
So bigger engine on 4Metre boat
You should PM Phil davies as we've had this conversation about 4m boats with big engines for ages now, there's a list of things you need to take into consideration when fitting a bigger engine to a small boat, weight to power ration, extra fuel, insurance, trailer, transom, position etc.