Repairing cracks in grp under stanchions - Baseplates Deckplates?

[FairweatherDave]

The stanchions have been removed and some soggy balsa removed..... its a Westerly......
Q1. I was going to simply fill the holes with thickened epoxy and redrill the holes for the stanchion bolts. And use butyl. I was going to just widen out the cracks back to solid fibreglass. But would the thickened epoxy constitute an adequately strong repair or should I be bridging the cracks with fibreglass matt, ie making a small patch? Really not sure whether to just go for thickened epoxy as a repair that will cope with compression loads but not necessarily leverage if the stanchion gets abused. (been reading the West system download).

Q2. Deckplates and backing plates. To spread the load I was going to reuse the backing plates which I think are aluminium. I have also seen stainless sheet rectangles used directly under the stanchions. That looks really good structurally but is it overkill. Opinions or pointers to more detail on backing plates and deckplates would be great. (I did read one suggestion of using chunks of premade fibreglass as backingplates, so I'm on the look out if anyone is local to Brighton.....).

Thanks for any replies.

 

[Concerto]

On my Fulmar, I opened the drilled holes to ensure a clean hole. If the wood is rotten, then spin a small alum key in a drill to remove any soft material. Seal the bottom of the hole and pour in some antifreeze to dry any residual moisture. Drain and leave to dry. Seal the base of the hole again and fill the hole with epoxy and glassfire strands. Do not over fill as epoxy is very hard to sand. Any cracks in the gel coat should be ground out with a Dremel and then fill with Plastic Padding Gel Coat Filler. Finally sand and compound. Finally drill new bolt holes. Butyl rubber is a very good sealant. The normal underside support is to use penny washers, but adding extra load spreading is worthwhile. A number of other forumites use plastic chopping boards, but plywood, aluminium or stainless can be used.

 

[FairweatherDave]

Thanks Roger, hadn't come accross the antifreeze trick.
Thinking overnight re the lateral strength issue I think that is answered by using some chopped strand mat in the epoxy, as well as decent backing plates. I am a little reluctant to use stainless deckplates on top for cosmetic reasons but certainly there are slight depressions on the deck on the inside of the stanchion base. I'm going over to photograph today (this time with a charged camera).

 

[Spuddy]

My memory is a bit hit and miss but I've got an idea that chopped strand mat doesn't wet out out at all well in epoxy; summat to do with the binder not dissolving. Mebbe somebody else can confirm or deny

 

[Quandary]

My memory is a bit hit and miss but I've got an idea that chopped strand mat doesn't wet out out at all well in epoxy; summat to do with the binder not dissolving. Mebbe somebody else can confirm or deny

For epoxy the mat should be powder bound, but if it is only a few strands I think either might do, it will be fine as long as the epoxy wets the strands, I know it it sounds like heresy but it is not essential to use epoxy for everything, the polyester/fibre premix sold in tubes by Plastic Padding should be adequate for this.

 

[FairweatherDave]

Did a proper inspection today. I have gory photos to upload if anyone wants to see them.......
And re-read more of the West system stuff. Looks like micro-fibres (West 403) or colloidal silica (406) will do the job. I will be using epoxy as I already have most of it and I am more confident with it. I am interested no one has advocated deckplates between the stanchion base and the deck however I think some chunky plwood as a backing plate will be good for strength, bedded in with epoxy as per the advice from Old Saltoz I found in another thread......(always feel confident with Oldsaltoz posts )
"Any repair to the gel coat should be left until the base has been properly repaired.
First establish what is under the stanchions, ply moulded into the glass is common, composite can be a problem if not stiff enough, no backing plate or poorly bedded plates can also be problem.
Repairs are best done from inside to preserve the original deck finish. Most repairs involve re drilling the bolt holes oversize and filling with epoxy and micro fibres, then re drilling to the required size, this ensures no water will enter and provide a non compressible base for the bolts; to prevent movement in future you need to good backing plates to stiffen everything up.
All backing plates should be bedded in with resin thickened with micro fibres (not balloons) left to cure then tightened fully."

Finally, has anyone else used the ethylene glcol antifreeze trick for drying any left over dampness in the balsa not removed with an allen key in a drill? I found this link on the wooden boat forum
http://forum.woodenboat.com/showthr...e-glycol-(auto-antifreeze)-treated-wood-safey
To follow Concerto's advice I think I might find it hard to plug the holes underneath as I used a hole saw in the lower skin of grp to remove soggy balsa so I have holes the size of a 2p piece.

 

[Concerto]

The advice about antifreeze was from an article in PBO for the repair to a soggy balsa cored deck, possibly on an Arperge. Maybe someone can remember which issue the article appeared in within the past couple of years.