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mikeb
90 Posts |
 Posted - 17 Feb 2013 : 21:20:34
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I'm not confident about the state of my transom, so I had a poke about at it today. And I'm not really any the wiser for it. It's definitely very soggy in there - everywhere I poked was saturated with water. But the balsa wood only seems to be about 10mm thick, the rest is quite solid (couldn't tell what it was made from, quite possibly fibreglass). I thought the transoms were supposed to be two skins of grp with just balsa wood in between?
This one has clearly had some work done to it in the not to distant past, but I'm not sure how well it was done. All the holes pictured (outboard mounting holes and outboard well drain holes!) expose the balsa wood, so it was always going to fill with water.
I think I need to open it up to investigate further, I was planning to cut along the red line, is this the best way? What is the extent of the balsa wood filling in the transom, is it just a bit wider than the outboard well or does it go all the way to the sides?
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nigel-in-oxford
United Kingdom
643 Posts |
Posted - 18 Feb 2013 : 14:33:20
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I have done a few of these now. you are right to cut along that red line.
continue out to the corner of the transom maybe 2-3 inches in. cut the outer shell out so you take the entire back outer shell of the transom off. clean out all the balsa rotted or not. you need to keep the outer skin, which you can repair on the bench. re attach the skin the best you can, I have taped it into place and also stuck it back with gelcoat filler, probably a mixture of the two would work better. I should have said that it is best to cut off the top flap of the transom (on your red line) so you can then pour in a mixture of fillite and chopped strands in resin with about 5% styrene to thin the resin. you can pour about 1l at a time keep the mix flowing. if you have the mix right it will not over heat, the fillite causes a dilution of the resin that helps with the heat. remake the top of the transom with s strip of chopped mat and finish with white top-coat.
chase out the joint on the outer skin and fill with top coat or gelcoat filler.
Have fun.
Swin Ranger 22 "Chronophage" (Time eater)
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mikeb
90 Posts |
Posted - 19 Feb 2013 : 13:20:03
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Are you saying that I need to remove the whole outer skin of the transom, all the way to the side of the boat??  I thought it was possible to just remove the top and scrape out all the balsa, and then fill with resin?
Where is a good place to buy the resin, fillite, etc materials online? |
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merlin
United Kingdom
400 Posts |
Posted - 19 Feb 2013 : 20:12:27
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quote:
Originally posted by mikeb
Are you saying that I need to remove the whole outer skin of the transom, all the way to the side of the boat?? I thought it was possible to just remove the top and scrape out all the balsa, and then fill with resin?
Where is a good place to buy the resin, fillite, etc materials online?
I used these guys very good service
www.fibreglassdirect.co.uk
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nigel-in-oxford
United Kingdom
643 Posts |
Posted - 20 Feb 2013 : 12:02:25
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yes take off the whole of the transoms outer skin. it is so much quicker than trying to scoop out the crud from the top. go to about 3" of the sides.
I have used :
http://www.cfsnet.co.uk/
for years very fast delivery, or pick up yourself if you are ever in Cornwall
Swin Ranger 22 "Chronophage" (Time eater)
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mikeb
90 Posts |
Posted - 20 Feb 2013 : 14:23:59
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| Thanks for that - I live in Cornwall, know exactly where their industrial estate is! |
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Jimbo
United Kingdom
585 Posts |
Posted - 20 Feb 2013 : 16:33:12
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Hi there.
Having in the last two years replaced the complete transom on a Birchwood 25 Widebeam, my advice is to remove one complete width of transom, preferable the inner one. Completely clean out all of the wet and rotten crud and allow to thoroughly dry out. Carefully cut to size a piece of Marine ply to the exact outline and if necessary laminate two pieces to achieve the required thickness. An alternative is concrete shuttering plywood with is coated with a pheno;ic resin waterproof coating which needs to be sanded off on both sides for the resin to adhere to. This ply is much cheaper than Marine ply but is of excellent quality. When the time comes to resin in the new transom, thoroughly clean and abraid the GRP hull surface to which the new wooden transom will be fixed to. Very heavilly coat the outer hull and new transom with resin and fix and hold in place with supports while the resin goes off. It will get hot. Then repeat this process with the cut out inner GRP transom and use plenty of chopped strand matting and resin around the joint especially at the botom, Do not cover the top face/joint with matting or resin yet. When cold mix a large amount of resin and pour in at the this open face until no more will go in. This will fill any voids. A piece of folded stainless steel or 6mm aluminium placed over the area where the outboard goes will spread the weight and loading. Hope that this helps. |
Edited by - Jimbo on 24 Feb 2013 18:15:04 |
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mikeb
90 Posts |
Posted - 20 Feb 2013 : 21:14:24
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Very useful info, thanks.
Can I cut the GRP with an angle grinder if I'm careful, or will I end up with a gooey mess? |
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Jimbo
United Kingdom
585 Posts |
Posted - 21 Feb 2013 : 09:02:46
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| I would have thought so if you are carefull. |
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merlin
United Kingdom
400 Posts |
Posted - 21 Feb 2013 : 09:18:25
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four ins grinder with a tile cutting blade
quote:
Originally posted by mikeb
Very useful info, thanks.
Can I cut the GRP with an angle grinder if I'm careful, or will I end up with a gooey mess?
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df
United Kingdom
5990 Posts |
Posted - 21 Feb 2013 : 17:45:25
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Inox disks are good for making a thin cut through grp, wear a dust mask though as well as a face shield.
A good rub down with dry soap before starting can keep a lot of glass dust out of your skin.
NBAS--The communal colostomy bag of the boating community.
Visit leomagill.co.uk |
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adi-n-chez
United Kingdom
1980 Posts |
Posted - 21 Feb 2013 : 20:42:00
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quote:
Originally posted by df
Inox disks are good for making a thin cut through grp, wear a dust mask though as well as a face shield.
A good rub down with dry soap before starting can keep a lot of glass dust out of your skin.
Chuck away paper overalls with elastic wrists/ankles are a boon too ! (also good for antifouling)
Adi
Sewer Tubes ? I'd rather have a D**ncr*ft (Only Kidding) |
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mikeb
90 Posts |
Posted - 22 Feb 2013 : 10:42:05
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So I should probably be cutting out the outside skin of the transom along these lines as well:
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nigel-in-oxford
United Kingdom
643 Posts |
Posted - 22 Feb 2013 : 11:13:29
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take that red line sideways to 2-3 " from the side of the boat, then the same distance right round the transom to the other side. your corners are a bit close to the bottom of the boat.
Swin Ranger 22 "Chronophage" (Time eater)
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Edited by - nigel-in-oxford on 22 Feb 2013 11:42:43 |
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tigtog
United Kingdom
421 Posts |
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mikeb
90 Posts |
Posted - 24 Feb 2013 : 13:46:56
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Cut the top off for an explore:
The transom construction seems to be about 10mm of balsa wood sandwiched between GRP. There is also a peice of ply for stiffening, mounted internally, glassed onto the inside of the transom where the outboard mounts. Is this normal/original?
I've scraped out the top 4-6 inches of balsa and most of it is rotten. The bits that are relatively sound are still saturated in water. The plywood is also starting to get a bit squidgy, should I replace that as well (Not sure how to get access to that though, the outboard well covers it from the inside).
Guess I'm gong to need to cut out the whole transom next?  |
Edited by - mikeb on 24 Feb 2013 13:48:02 |
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