Help/Advice - Found crack along transom of my ally project boat...gutted
Nasty surprise this morning when I pulled off the transom plywood packing on my project boat. There is a crack in the aluminium 'skin' of the transom. It runs horizontally and lines up with the bottom of the main support spar that runs accross the transom where the top outboard mounting holes are. I assume that the outboard has been slightly deforming the spar when under power, and over its 30yr life this has fatigued the attached aluminium skin to cracking point. THe crack runs for about 500mm in the middle of the transom, a bit wider than the ouboard mounting bracket. All the structural spars (not sure if that is the correct term) and supports on the inside of the transom seem to be okay.
I realise any transom damage shouldn't be taken lightly, but just wondering if anyone can tell me just how serious this is and also offer any advice on repair strategy. Would it be okay (possible) to seam weld along the crack and possibly along the bottom of the spar on the inside to reattach it? Or would it be better to weld a bracing plate accross the whole back of the transom? I've attached some photos to try show where the crack is. The first is from the outside of the transom and the second from inside the 'wet well' looking backwards.
Any advice from those with boat building or repair knowledge would be greatly appreciated. Any recommendations for repairers would be great too. (ideally NOR). I've put in so many hrs on this boat already, not to mention $ and I'm really hoping this is not too serious or expensive....
carnarvonite
Posts: 8669
Date Joined: 24/07/07
Weld
I'd run a line of weld along the crack then weld a thick plate over top of it to stiffen it all up and hopefully prevent it forming again
grantarctic1
Posts: 2546
Date Joined: 03/03/11
Clean up
Clean up the crack with a grinder,inside and out ( use parifin or candle wax on the disk to help with grinding) Then stainless steel brush before welding it up. Weld inside and outside ( i assume you are welding the boat yourself ? ) You can then flush off the outside weld.
If the top tube were the motor bolts on, is welded to the transom(on the inside) this might have caused the cracking to start and you might need to cut it out and replace it .
Going buy your pictures, you could add some gussetts or some type of bracing to help strengthen the whole area. I would not only be looking at the repairs needed but also what has failed and caused the problem .
Unfortuantly there are not many easy answers when it comes to Aluminum repairs, the older the aloy the harder to fix .
I'll wach your thread and see how you go , hope this helps. Cheers Grant .
tigerfish
Posts: 88
Date Joined: 20/08/10
Cheers for the advice grant.
Cheers for the advice grant. Not welding myself (only have a stick welder and no experience of TIGanyway) but I have a couple of small holes that need filling and two broken welds on one of the seat supports between deck stringers so was going to find a boat repairer/ally welder to do those, and can hopefully get them to do the inside and outside weld as you suggest.
glastronomic
Posts: 892
Date Joined: 16/02/11
As Grantartic1
As Grantartic1 suggests.
Sounds like you do not weld ally, so get it done by a pro who has the equipment, or sell the boat off if it is all to much for you.
Still have the Bimini and want it gone, here.
tigerfish
Posts: 88
Date Joined: 20/08/10
Cheers glastro, yes
Cheers glastro, yes definitely going to get a pro to do the welding. On second inspection yesterday i've decided it is probably not as bad as I had first thought as it is just where the ally skin on the transom attaches to the main top cross-member in the outboard 'wet-well' area. The cross memeber itself and the v-shaped supports below for the bottom mounting holes all seem to be pretty solid, so I'm hoping that as long as I can get someone to weld it as grantarctic suggests, it should be okay. Might also look at getting a plate welded accross the whole area, maybe the same size as the plywood packing to shore it all up.
SOrry, I have been a bit slack with getting in comms about the bimini. I'm definitely still initerested. I'm around the rest of today or otherwise during the week after about 4:30pm - just let me know when would suit you and where I will come over. THanks