Replacing rubbing strakes grp yacht

[Hushinish]

I want to replace the rubbing strakes on an Hawksbill 24 GRP Yacht, they are some sort of hardwood, now mushy, painted by previous owner.

My Worry is that the deck moulding seems to lip onto the top of the hardwood and finishes i a rough mishapen edge and look unsightly, am worried about 'can of worms senario'

Any advice?

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[ROCKETSHIP_11]

VETUS DO A GOOD RANGE OF RUBBER RUBBING STRAKES EASY TO FIT CHECK IT OUT http://www.vetus.com/

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[Hushinish]

Thanks Rocketship, can't see on that site though, plus it's a USA store so delivery might be expensive.

Have investegated further and found the exising RS's are of Parana Pine (not very durable for marine use) and are bolted with those roofing type galvanised bolts with a pan head with a flat cross slot. Deck moulding laps on top of RS covering the top, in the horizantle joint between RS and deck moulding, lots of moisture lurks.

Me thinks, take off RS, make a new one out of quality hardwood with grooved back into which deck moulding fits.

Concerns, Bending Hardwood, Getting the old bolts out, no nuts visable. anyone done this type of repair?

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[bob_tyler]

Try http://www.vetus.co.uk and order their brochure. You will probably get what you want. They have a great range.

 

[Richard_Blake]

Sounds like a possible can of worms. Did one long ago on a friends GRP 20-footer that wasn't very well built. Job expanded, laughing at the time allotted.
Issues:
How is deck bonded to hull moulding? Does the latter curve its lip in under the deck lip which comes over or into the RS, or does it stick it's bottom lip out with the deck lip, as it were? If the latter, the RS may not be simply such - but also (semi-) structural.
And if it's looking ragged, is the bond still good? Are they well glassed together
somewhere inside? What's hiding those nuts? Liberating those may be a can-of-worms job, meaning removing some interior trim.
If she's well-built, the nuts should be accessible somehow - if she's not (I don't know the boats) they may have been lazily glassed over.
When you pull the wood away, do the bolts wobble or stay solid? If they stay really solid (are therefore glassed in behind somehow) and have enough thread up their length, how about cutting off the heads, getting nuts to fit, pre-drilling the timber (carefully), boring out so nuts and washers are countersunk, and slipping the timber over them then tighten up. Choose a really good adhesive-type bedding compound. Not ideal - better to really know what's happening in behind the joint - but might save ripping out stuff down below.

Unless she's an extreme shape, I wouldn't have thought bending the timber would be too much of a problem if you choose a suitable timber. Others can advise on that better than I.
Grooving the back is easy enough with good equipment (table saw or table-mounted router) but if you're not confident shouldn't cost too much if you chat up your local boatbuilder or carpenter and get him/her to run it through a shop machine. Better result than a hand-held power tool with wobbly bench and the cat under your feet. You do NOT want a wavy groove.
Best thing, of course, is if there's someone out there who knows the boats!
Good luck
Richard

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[Hushinish]

Thanks Richard, you've grasped the facts and given this some thought! Starting from top, we have fresh air, then the deck moulding in the form of an upstand say 25mm up and 25mm out, it ends in a feather edge, and is only say 4mm thick, Below that, silicone sealant/gunge then a 30mm x 75mm RS. Internally there are no nuts visible, but a raised area possibly glassed in timber batten. the hull/deckbond is internal, I think

I am a joiner! and you are bang on regarding taking the heads of the bolts and hoping to pre drill new rs's and bolt, glue in place. My theory is that if the nuts spun, then the bolts would turn now, I might drill the heads off, then proceed as you suggest.

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[ccscott49]

If you can get at the inside, could you not just replace all the bolts, I mean cut the old ones off, redrill in a new spot and put stainless coachbolts through the RS to hold it on, then you are sure you have a proper job, I would reccomend using iroko for the RS, or even larch, bond it on with sikaflex ahesive/sealant, firstly encapsulating the iroko or larch with thinned epoxy resin and allowing to dry. De-wax the RS/epoxy with meths before bonding it on. The pait with a good two pack paint, jobs done and will stay done. By the way, paint the ends of the cut off bolts with cold galvanising zinc paint before fitting the new RS, saves rust streaks later. Hope this helps. IMHO

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[Richard_Blake]

Agree with Colin completely. That way you know you're actually strengthening the whole caboodle.

One thought: You say "25 mm up then 25 mm out" - do you mean that the moulding goes up from the side deck and then outboard-wards? What about scuppers? Might it be an idea, depending on exact layout, to do it in two pieces rather than grooving?... a RS under the lip and a sort of capping rail above it extending further inboard than the original? Could turn out prettier too. You could screw extra cleats and gizmos to it!
Richard

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[oldsaltoz]

G'day Richard,

Replacing your rubbing strake should be pretty straight forward, the only worms in the can you refer you may be the holding bolts, but relocating the fixing point is not a huge problem, chances are you will be adding a couple to get the strake to line up just right anyway.

You are lucky with the size being 35 x 70 mm, that's a standard size not too much machining to do.

Bending is not too difficult, just make sure you have a bit left over at the stern and fix from the bow working back, use the extra bit to pull the timber around.

When scarfing your joints, may I suggest you first apply some epoxy resin thinned (equal amounts of meths to resin, add meths last), brush it in till it will take no more, then add some gluing fibres to some more epoxy resin and clamp them, but not too tight, you want the glue to stay there, don't squeeze it all out.

Also avoid gluing the strake to the boat, it will make removal easy later.

If the timber you select is a bit stiff, you can router some off the inside, but leave at least 15 mm of the original timber on the outside edges, start with a shallow cut and get deeper as you work to the centre.

There you go. - - - - - -easy, well lets hope so anyway.

I hope this helps.....



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[Hushinish]

Thanks guys, some great advice here, Richard, the 2 part RS with top forming a capping occurred to me, but I will be left with a wee gap where the grp is sandwiched which would need caulking. I think I will router away the first 10mm of mushy grp leaving good, then set new strake higher with 13mm groove in back to accept the grp lip. Existing scuppers are 2 x 25mm tubes inset in the upstand/RS

I like the Iroko idea mr Scott, great advice all round, just need to get my head into the aft lockers and see if I can get to bolt the things into place.

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[Hushinish]

Stop press!!!

Just enjoying a cold beer after a rewarding afternoon taking off the offending parana pine rubbing strakes. The Deck/Hull don't lip onto the top of the RS as I had at first thought, the kit builder had lost plot presumably because he had struggled to bend the rs to the shape of the hull and filled the gaps with squirty foam, putty, epoxy filler and then lapped grp over top of RS and onto the deck. The whole affair came away easily and was full of black dirty water.

So fresh advice now needed. My hull deck joint is good and stands about 50mm up from deck. It is bolted together with 6mm ss bolts. the 10mm heads and nuts stand proud at both sides, Is this normal construction?


Elsewhere on the forum I have read about an upside down 'L' shaped iroko rubbing strake, I like this idea, but don't like the batten I would need on the deck side of the hull deck joint to hide the unsightly nuts and bolts. unless it is sealed well, water would be trapped in the joint, what's the normal soloution?

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[ccscott49]

Re: Stop press!!!

Fill the joint with sikaflex caulking compund, prepping the area first, with primer to get it to stick prpperly, this is different stuff from the sealer, adhesive I reccomended for fitting the RS. This stuff stays more flexible and moves with the boat.

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[Richard_Blake]

Re: Stop press!!!

Satisfying, stripping off the nasties, isn't it!
Sounds like it's now just best practice for sealing and capping a standard GRP joint, so I'll bow out, being a simple wood person.
Good luck
Richard

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