Transom bolts and sikaflex.

[kerny]

After reading some old posts on water getting into the transom I decided to check my rib, first I checked the engine bolts and found that they had no sealant on them. I took them out one by one and then applied sikaflex inside the bored holes and on the bolts and washers before putting them back in. Should this be an ample enough job to protect the marine ply inside the transom ?? the reason for asking is that I have just come across an old thread suggesting flow coating the holes first then use sikaflex doh I don't fancy starting again, but I will if I have to.

[Chris]

Sikaflex will be fine if you have put plenty in there. Not many people flow coat their holes apart from Wilfish of course.

[chewy]

Be better if you did flowcoat them or put resin on but sikaflex will do.
When I've used it in the past I've put it on and done the bolts up finger tight, let it go off and then nipped em up so your compressing cured sealent.

[Dirk Diggler]

Flowcoat is a waste of time, as when you tighten the bolts, the transom will compress a little, but the flowcoat won't, but it will crack.

Resin isn't waterproof, so that's no good either, although it's probably better than nothing. I use Epoxy on the bare timber, then I use Sika below the waterline, and silicone above.

[kerny]

Originally Posted by Dirk Diggler

Flowcoat is a waste of time, as when you tighten the bolts, the transom will compress a little, but the flowcoat won't, but it will crack.

That makes sense to me, I presume then that you cannot protect the marine ply 100% and that as long as it's minimal seawater getting to the timber it won't be much of a threat as long as you protect it the best you can and give it a regular hosing down with fresh water.

[captnjack]

Originally Posted by kerny

That makes sense to me, I presume then that you cannot protect the marine ply 100% and that as long as it's minimal seawater getting to the timber it won't be much of a threat as long as you protect it the best you can and give it a regular hosing down with fresh water.

Freshwater is actually more likely to cause dry rot. You won't be able to "rinse" the ply anyway.

I have no idea what flowcoat is but 3M 5200 polyurethane has a proven track record for sealing thru-hulls, transom bolts and similar applications.

[C-NUMB]

Litle off topic but my Yam 90 transom bolts was well sealed with sika. Removed the bolts, nothing happened, engine did not move. Tried to lift the engine a litle, boat followed....Had no other option than to separate the engine from the transom with a chisel ? Sika is pretty strong stuff...As mentioned, plywood do get compressed so what ever is used to seal the hole, its good to be flexible.
Dont know if impregnate the holes with some type of wood oill(owatrol) would be any good before sealant, never tried.

[mister p]

Depends how much "play" is in the transom and how prepared you are to fix/maintain or replace.
If you are stopping the rot, as it were, then drip linseed oil in until it weeps.
if it's not too bad, still keeps strength etc., then stopping further water ingress is the deal.
Ultimately it's a stop gap, but silicone into the gaps helps. You need to be happy that you're not stopping it drying out by doing this!
If you've got water in your transom ply............apply low heat to dry it out, seal and if it still keeps it's strength, seal to prevent further damage.
But I reckon if you think it's been soured, then make a plan for replacing it, keeping it OK for the while.
Damage limiltation etc., if the timber's wet then replace it.

[kerny]

Originally Posted by mister p

But I reckon if you think it's been soured, then make a plan for replacing it, keeping it OK for the while.
Damage limiltation etc., if the timber's wet then replace it.

Nothing like that... this is more preventive than a cure.

[mister p]

Glad to hear it.......it's a hell hole otherwise

[hadd]

That silkaflex might stop someone nicking your engine kerny even if they cut the bolts Yam 90 transom bolts was well sealed with sika. Removed the bolts, nothing happened, engine did not move. Tried to lift the engine a litle, boat followed....Had no other option than to separate the engine from the transom with a chisel ? Sika is pretty strong stuff..

[eoin1981]

am i right in saying that a general silicone sealent is no good for the job and you have to use sikaflex?

[kerny]

Originally Posted by eoin1981

am i right in saying that a general silicone sealent is no good for the job and you have to use sikaflex?

[Erin]

Originally Posted by kerny

Disagree actually. Whilst Sikaflex is far better as an adhesive, properly applied quality silicone would be just as good, possibly even better as it has a much lower modulus and will therefore accomodate more twisting, flexing or stretching before it parts company. I would say either sealant is fine so long as it is well applied and the surfaces it was applied to were clean.

[tony t]

Originally Posted by Erin

Disagree actually.

That will be you off his christmas card list you know how touchy them Germans are

[Divertris]

On fitting my new elephants trunk yesterday I used a Marine sikaflex to seal the hole I had drilled with the hole saw applied with a finger (gloved finger) prior to gently tapping the pipe into the hole and sealing at both ends. Prob a better seal than a bolt but the main thing I would say is getting plenty pf sealant in there so when the bolt is pushed through there is still sufficient sikaflex in there to coat the surfaces to create a good seal. Bargain for the Sikaflex 291i at my local 'Scott Bader' £5.51 +VAT for a 300ml cartridge.

[Divertris]

The sika 291i looks like the perfect stuff for the job:


Applications for Sikaflex 291i 300ml- Marine Sealant.

• Bedding of Deck Hardware
• Sealing & Bonding Above and Below the Water Line!
• Can be used as a general sealant
• Sealing plumbing and sanitary equipment sealing joints including keel/hull, stern shaft tube, bonding deck to hull
• Excellent for bonding anti-slip man-made decking materials including Marine Deck 2000

Advantages & Benefits of Sikaflex 291i 300ml Marine Sealant:

• Use above and Below the Water Line
• Resists Salt Water
• Fast Strength Build up
• Stable
• Paintable
• Sandable
• Excellent Bond Strength
• May be squeezed or brushed into place

[Maximus]

Originally Posted by Divertris

The sika 291i looks like the perfect stuff for the job:


Applications for Sikaflex 291i 300ml- Marine Sealant.

• Bedding of Deck Hardware
• Sealing & Bonding Above and Below the Water Line!
• Can be used as a general sealant
• Sealing plumbing and sanitary equipment sealing joints including keel/hull, stern shaft tube, bonding deck to hull
• Excellent for bonding anti-slip man-made decking materials including Marine Deck 2000

Advantages & Benefits of Sikaflex 291i 300ml Marine Sealant:

• Use above and Below the Water Line
• Resists Salt Water
• Fast Strength Build up
• Stable
• Paintable
• Sandable
• Excellent Bond Strength
• May be squeezed or brushed into place

So..Chris was Right in the first place!

[C-NUMB]

The Sikaflex 291i(i-cure) is IMHO very different from the stuff before i-cure times... The old stuff bonded stronger. This can be good or bad, pending on application. As a sealant guess its even better as easier to remove case needed.

Hope that 292i (i-cure) have not lost the original properties of 292 that much.