Timberwolfy 62 Posted October 15, 2017 Share Posted October 15, 2017 Hi All! Inexperienced new owner here. I've got a keel-stepped mast on a GRP boat (Stratus 747). My forward hatch and the mast both leak a little (they're on the to-fix list), and the water coming in has softened the keelson enough that it is compressing/cracking around the base of the mast (right-top side of it in the pic is the worst of it). More experienced friends have had a look and so far no one is panicking, but we all agree it's a problem that needs fixing. An idea I'm liking a lot is adding a steel plate along the keelson to reinforce the wood and spread the load, but this would also then require some kind of barrier between the steel plate and aluminium mast. One suggestion was an ice cream container, since that would then catch any leaked water and I could sponge it out easily. Anyone else have thoughts? Thanks in advance Quote Link to post Share on other sites
Black Panther 1,584 Posted October 16, 2017 Share Posted October 16, 2017 Aluminium plate? No problem with dissimilar metals Quote Link to post Share on other sites
Dambo 44 Posted October 16, 2017 Share Posted October 16, 2017 FYI, she's GOP (Glass Over Ply) not GRP (Glass Reinforced Plastic) David, the aluminium would have to be pretty thick compared to say mild steel...? Quote Link to post Share on other sites
Beccara 25 Posted October 16, 2017 Share Posted October 16, 2017 I think rule of thumb is twice the thickness for mild steel to aluminum conversations Quote Link to post Share on other sites
madyottie 82 Posted October 16, 2017 Share Posted October 16, 2017 Doesn't quite relate, but someone might get a laugh... Racing a Fireball on the lower Severn river, 25+ knots, 6 foot waves. The rig started to go a bit soft, so tightened it up a bit on the first downwind. End of the next beat it was loose again, assumed the clear was slipping a bit, so pulled it as hard as I could. By the end of the race it was all floppy again, and the boom seemed to have got a bit lower. Once ashore we discovered that the hog had got a little moisture inside, and we'd split it down the middle, and the mast step had worked its way about 50mm down the split, and was trying to escape out the bottom. We won the race but our series was over ???? 1 Quote Link to post Share on other sites
Black Panther 1,584 Posted October 16, 2017 Share Posted October 16, 2017 Thicker but lighter? And won't rust. Or dry out the wood and run some sexy carbon up and down it?? Where are all the boatbuilders? Quote Link to post Share on other sites
Timberwolfy 62 Posted October 16, 2017 Author Share Posted October 16, 2017 FYI, she's GOP (Glass Over Ply) not GRP (Glass Reinforced Plastic) David, the aluminium would have to be pretty thick compared to say mild steel...? awww bugger I thought GRP was Glass-Reinforced Ply... it made sense in my head. I would very much like my mast to not escape out the bottom Quote Link to post Share on other sites
Black Panther 1,584 Posted October 16, 2017 Share Posted October 16, 2017 I assume when you bought it you had a survey that made sure the damp spot didn't extend further? If not go crazy with a small hammer or the handle of a screwdriver tapping everywhere and listening for dull spots. WHich is not relevant to the question asked but thought I'd throw it in. The good thing about GOP (glass over ply) is it is very easy to work with and repair. Quote Link to post Share on other sites
Timberwolfy 62 Posted October 16, 2017 Author Share Posted October 16, 2017 Fix the leaks first or sooner rather than later. yup, mast first, hatch second... hatch should be as easy as pulling it out and re-sealing it. key word: should. Quote Link to post Share on other sites
erice 732 Posted October 17, 2017 Share Posted October 17, 2017 bill probably got some carbon "armour plate" about 1cm thick, from that mast section you need some carbon bling Quote Link to post Share on other sites
raz88 96 Posted October 17, 2017 Share Posted October 17, 2017 Isn't carbon prone to causing corrosion in metals it touches? I'm curious to see all these suggestions of using carbon in a base for an alloy mast... Quote Link to post Share on other sites
Vorpal Blade 89 Posted October 17, 2017 Share Posted October 17, 2017 I think chopping out the soggy bit and inserting a piece of hardwood there would be the best solution, adding carbon in that region will only lead to different problems. Quote Link to post Share on other sites
Island Time 1,235 Posted October 17, 2017 Share Posted October 17, 2017 Timber, preferably laminated, properly scarfed in, glassed over. Allow drainage from mast - water comes in the halyard entries, and must come out somewhere. Quote Link to post Share on other sites
Black Panther 1,584 Posted October 17, 2017 Share Posted October 17, 2017 Put mast drainage at deck and seal the mast. Don't want fresh water inside a ply boat. Quote Link to post Share on other sites
Timberwolfy 62 Posted October 18, 2017 Author Share Posted October 18, 2017 thanks all for the feedback! I have a lot to think about... looking to do this project ASAP. will have a chat with some people and do some reading. I found this site, which I thought was really interesting, if anyone is into the chemistry aspect of this subject: https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556 Quote Link to post Share on other sites
Bad Kitty 252 Posted October 18, 2017 Share Posted October 18, 2017 I'd cut it out till all the soft & rot is gone sorry. Putting a bit of ali or steel over the top is just a Band-Aid. It's a bit of a drag having to lift the rig, but once it's done its done. And it's only labour & a bit of timber & epoxy, you won't need a whole lot of expensive parts. Quote Link to post Share on other sites
John B 106 Posted October 18, 2017 Share Posted October 18, 2017 Doesn't quite relate, but someone might get a laugh... Racing a Fireball on the lower Severn river, 25+ knots, 6 foot waves. The rig started to go a bit soft, so tightened it up a bit on the first downwind. End of the next beat it was loose again, assumed the clear was slipping a bit, so pulled it as hard as I could. By the end of the race it was all floppy again, and the boom seemed to have got a bit lower. Once ashore we discovered that the hog had got a little moisture inside, and we'd split it down the middle, and the mast step had worked its way about 50mm down the split, and was trying to escape out the bottom. We won the race but our series was over The Keeler famous for something similar was the A class Tamatea, . She ended up with a hog in her sheer at the chainplates for life . Which ended sometime in the 2000's when she was vandalised and burnt in storage in west Auckland. I have a deck stepped mizzen in my boat, over 40 odd years the step had worked and cracked the ply under it ( the cockpit sole) I ended up cutting out about a square foot ( the kauri underneath was pristine) and just scarfing a square of kauri back in. Worked like adream and was just plain fair wear and tear for all those decades. So I reckon you just cut back to clean timber and rebate a block of hardwood back in on to that keelson/ step. Glue it and screw it.( minimal screws,silicone bronze is pretty inert.) Quote Link to post Share on other sites
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