Adrian Franks with Mirage 28 MK2 No 417 wrote to me recently with the problem that when the rig was tensioned, the saloon door would not close. This reminded me that we had the same problems from new with Dawn Treader. As this may be a more common problem than I realised I thought it worthwhile to publish my reply to Adrian.
“The mast post was attached to the port half of the saloon bulkhead at the joinery works and the complete unit glassed to the deckhead and screwed to the upstand in the floor moulding. This gives two problems, (1) There is usually some gap between the top of the post and the deck, with the mast compression taken by the ‘L’ shaped bonding along the top of the bulkhead. (2) There is usually little under the floor moulding to take the compression down to the hull.
To deal with the problem I cut the bonding away round the top of the mast post, glued in wedges between post and deck and re bonded. At the base I cut out the shower tray and was then able to wedge and glass between underside of floor moulding and hull in way of the post area and did not re fit the tray but bonded down to the hull, all round the edges of the hole left in the floor.
I also took off the cover strip between deck head and the saloon side of the bulkhead and bolted a 2” by “ steel strip (curved to fit the bulkhead) behind the cover strip, with large washers on the other side of the bulkhead.
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This provided a cure and I imagine other owners may have the problem in greater or lesser degrees depending on how well the bonding was done in the first place. Also the trouble may appear with time if the original bonding starts to break down due to being overstressed.
A tip worth passing on is that glassfibre resin (polyester) is wonderful stuff for bonding to glassfibre, particularly if you wipe well with acetone first, but it does not stick very well to timber and the bond can be improved by coating the wood first with resin and allowing to cure and then bonding to this ‘primer coat’. It seems that if you do not do this, but bond direct, the resin soaks into the timber, leaching it out of the mat and giving a dry joint and thus a poor bond.
Whilst on this subject, do not buy glassfibre mat at great expense from a chandlers but look up in Yellow Pages for your nearest glassfibre moulders, they will usually give you their offcuts for nothing and you only need small scraps when undertaking repair jobs. Also this mat is usually thicker than the puny stuff you get in the shops.
The same moulders will also sell resin and catalyst and gel coat at advantageous prices but take your own containers. Re gel coat, if you need to use it to paint on top of a bare moulding it will not cure on the surface but remain sticky. Ask the moulders for some ‘wax in styrene’, add this to the catalysed gel coat (the same amount as the catalyst). This floats to the surface and seals out the air, allowing the gel coat to cure right through.
Mike
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