Hi Guys,

I have pulled the boat apart to do some work on it and are about to bolt the beams back on. Would it be a good idea to chuck some silicon (or a different bedding compound) down? Or would this make it too hard to get them apart if I ever wanted.

It will help, but don't apply the sealant as a glue or your beams will indeed be very hard to remove. I have personally made that error on my own F16.

Use just a tab of sealant around the bolt holes, more like putting down a very thin ring of sealant.

When the bolts are tightened the space between hull and beam will become very small and even the little sealant that you have put on their will quickly spread over a large area. And when a square cm of sealant take only 100 grams to break off then the hole beam landing being sealed up will still take several tens of kg's before you can remove the beam after unbolting it.

Been there, done that and you'll be amazed how much load a widely spread out simple sealant can take before failing. My timber hulls were making all kinds of heavy cracking sounds before it popped. So the less sealant you use the better.

Wouter

We have used soft rubber "o" rings before & they work well....alittle easier to get off also <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

I assume this is an issue becouse the beams are bolted through the beam seats with a nut on the underside. Why not glass over the nut and make the whole setup waterproof? Bummer if you strip the threads but waterproof is nice.

The bolts on the Taipan bolt into a block of aluminum that is glassed into the hulls. Half the reason I pulled the boat apart was to re-tap these blocks with a larger diameter bolt as the aluminum had striped itself. One of the reasons that I was thinking about siliconing down the beams was for the added stiffness that wouter was talking about.

silicon or sikaflex will do nothing to aid platform stiffness.

If you want to improve the beam hull join you should bog the beams into place. make sure you cover the beam in mould release before starting though...

If you glued the beams down with epoxy, you would gain stiffness, but that is not allowed under the F16 rules. If you think the fit of the beams is not too good anymore, re-seating them with thickened epoxy is an option, be careful though and not glue the beams or bolts in permanently <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Technically speaking if you bog the beams in place but have mould release on the beams - then the beams are not actually glued in place.?

Does than make sense?

That is right, but then you dont get the extra stiffness the A cats enjoy when they glue their beams in either?

If you bog the beams in with mould release on the beams so you can remove them you do get a BIG gain in platform stiffness.

What Macca says !

I think it is also referred to as "seating the beams".

Basically you make a very tight fit between the beams and beamlandings.

More tight then you can design into the hull mould.

Wouter

Bogging the beams is common wisdom and a well known technique. Still not as stiff as glued beams..

I believe Boyer/Geltek use gelcoat with a wax additive to seat the beams in, a short sharp hit with a rubber mallet breaks the seal when removing.

A friend of mine did the same (stripped the aluminium blocks, he put stainless steel helicoils in and still used the 8mm bolts.

Once you've put something in the beam/hull gap, what about the threads? What do you guys prefer to use on the bolts as a thread protector, corrosion inhibitor, thread lock (maybe?) and anti-seize? One would expect that with stainless bolts into aluminum threads this would be absolutely critical, would it not?

I have found wax paper or couple layers of saran wrap works well with an epoxy filler.
Vs mold release or wax on beam sticks/adheres a little bit, and pulls off some gel coat when pulling apart.

Wow, you actually agreed with Macca on something! Is this the start of a new trend?

But I actually used to replace the bolts every 2 yrs on my ol' Taipan and reseat the beams. Used same method Macca described.

Grease

I thought about doing it that way, but decided it would be better just going another size up (M10), From reports of other people who have done this it improves stiffness tonnes as well.

I use lanolin. When the aluminium blocks have stripped on my boats I drill the block out to the next size and bolt through using a longer bolt.

Darryn

Hi all,

I would recommend using commercialy available anti seize products on thread, when you have SS into alloy or even into SS. It means you can get them apart anytime in the future and doing them up very tight is less likely to damage threads also with anti seize on them.

Available in small tubes at most auto stores.

Regards Gary.