Fitting a teak rubbing strake

Danny Jo

Danny Jo

Well-Known Member
Joined
13 Jun 2004
Messages
1,886
Location
Anglesey
Visit site
Last year Freestyle had an argument with a pier while her crew were touring a distillery on Islay, so I've decided to fit a rubbing strake.

I was lucky enough to acquire some 55mm x 140mm teak deck planks off a Mersey ferry, and I've had them sliced up and scarfed together to make a rubbing strake 48mm x 38mm. I'm also lucky enough to have a wooden hull, so I intend to fasten it to the hull with two-and-a-half inch by fourteen gauge stainless steel wood screws at 200mm centres capped by about 18mm teak plugs.

Sikaflex for this lot (22m x 38mm) is going to cost an arm and a leg. On another thread, Vyv gave a link for a marine sealant which is sadly now discontinued. I believe PBO ran an article suggesting one could do the job with "No Nails", but not having access to a copy, I'm a bit reluctant to use a compound not designed for marine use.

Any suggestions?
 
About 4 or 5 years ago I removed and refitted some thick hardwood coamings to my coachroof and bedded them down on Unibond High Performance All Weather Frame Sealant It was easy to use and has shown no signs of deterioration. It is described on the cartridge as 'siliconised polyurethane sealant'.

I bought mine in B & Q and it was a lot cheaper than Sikaflex.

(web page). (and here)
 
Consider doing it the traditional way with white lead paste and linseed oil putty. Its as good as anything Sika whatsit do and a fraction of the cost.

About £35 for 3 kilos paste and a tenner for 3kilos putty. Add a drop of grease when mixed up.

Cheers

Colin
 
White lead paste and linseed oil putty is a very good idea, but I have two reservations.

Firstly, I imagine that it will harden. One of the benefits of modern sealants is the flexibility, which will spread the load on the hull if there is a point impact on the rubbing strake.

Secondly, I am concerned about the opportunities I am creating for water to enter the wood of the hull. This is the Achilles heel of wood-epoxy construction, which depends for its strength and longevity on the epoxy coat excluding water. Drilling through this for the fastening screw creates potential entry points for water. I was hoping to get away with capping the screws with teak plugs epoxied into place, and a long-lasting waterproof seal between the hull and the strake.

The counsel of perfection, of course, would be to fit the strake, then remove each screw one at a time, inject epoxy into the hole and replace the screw. Reluctance to do this is partly down to the work involved and partly the awful thought that one might at some stage want to remove the strake!
 
Were you pricing the Sikaflex in 300ml tubes? I use Saba adhesives for teak work, either Sealtack 750 or Deckfast MS. Both of these come in 600ml sausages and work out considerably cheaper than 300ml tubes. Deckfast will need a primer, especially with the teak.
 
Drill your holes at least 10mm larger than the fixing screw/bolt, fill the hole with a mix of epoxy resin and Micro-Fibres, let it cure and re drill to the required size.

This ensures the timber is sealed as well as providing support to prevent the timber crushing.

Hope this helps.

Avagoodweekend......
 
[ QUOTE ]
Drill your holes at least 10mm larger than the fixing screw/bolt, fill the hole with a mix of epoxy resin and Micro-Fibres, let it cure and re drill to the required size.

[/ QUOTE ] That sounds great for bolts. I imagine that conventional (conical) wood screws might have difficulty in epoxy, but I take it that chipboard type (cylindrical) screws are OK?

I've been going round removing deck fittings, drilling larger holes, epoxying in teak plugs and refastening into the plug - this gives me the option of removing the fitting for painting etc while at the same time preventing water ingress into the plywood of the deck. But I hadn't thought of that as suitable for longer screws.
 
[ QUOTE ]
Last year Freestyle had an argument with a pier while her crew were touring a distillery on Islay, so I've decided to fit a rubbing strake.

I was lucky enough to acquire some 55mm x 140mm teak deck planks off a Mersey ferry, and I've had them sliced up and scarfed together to make a rubbing strake 48mm x 38mm. I'm also lucky enough to have a wooden hull, so I intend to fasten it to the hull with two-and-a-half inch by fourteen gauge stainless steel wood screws at 200mm centres capped by about 18mm teak plugs.

Sikaflex for this lot (22m x 38mm) is going to cost an arm and a leg. On another thread, Vyv gave a link for a marine sealant which is sadly now discontinued. I believe PBO ran an article suggesting one could do the job with "No Nails", but not having access to a copy, I'm a bit reluctant to use a compound not designed for marine use.

Any suggestions?

[/ QUOTE ]
http://constructionchemicals.co.uk/acatalog/probond2000.html

Hope this might be of help.
C_W
 
[ QUOTE ]
screws + epoxy
the screws will never ever come out. even if you want them to.

[/ QUOTE ]

Screws or even bolts can be removed even if set in epoxy, just heat them and they will unscrew. I use a soldering on the head of the offending item.

Avagoodweekend......
 
There's normally someone selling out of date sikaflex at boat jumbles - is there one near you this weekend?
 
If you have got, or can get hold of a copy of Febs PBO, they did a good article on glues and sealants, starts on page 54, the polyurethane mastics could well be what you need? As long as you degrease the teak with a drop of Cellulose thinners or Acetone, "they will keep the water out like nothing else" "Excellent adhesive qualities also" Both quotes from the article.

Other than Sikaflex 291, they quote Evo-Stick "Nail and Seal", "Soudaflex", and CT1 as being very good, and are cheaper, as they can be obtained from builders merchants.

There are some that will scoff if a product isn't labeled for marine use, but, I always reckon that sometimes it's worth thinking outside the box?? I use a mastic that sticks to anything, and stays stuck, even to wet surfaces, dries to a flexible, but tough consistency, it also comes in various colours, for the life of me, I can't remember what it is called, but I will go to the workshop later and make a note of it if you want?
 
Sections of mahogany rubbing strake were replaced on my boat due to rot, scarfing in the new sections.
I used a polysuphide mastic with the brand name Life Caulk. It is semi permanent making future fixes easier; it can be sanded when set; it is available in white and in a mahogany-like brown.
Silicon bronze screws would be better than stainless steel if you can get them.
 
I certainly wouldn't use epoxy to seal the screws. I would use a dab of the same bedding mastic if you really want to bed them.
And I would use a polyurethane to ensure the best bond between the strake and the painted wood hull . Now the securing screws can be that much smaller. I would imagine that the wood/epoxy hull is a) actually quite thin for the purpoises of screwing into and b) perfectly impervious to water at the moment.
 
"Where No More Nails/Other grippers is/are to be used externally, it/they must be protected from driving rain, ponding water or permanently wet situations." From possibly the top of the range solvent/rubber based adhesives/grippers specification sheet.

Sikeflex is great if used within its exceeding short shelf life. I've used Vallance Clear Glazing Sealant to good effect with wood on wood; wood on gelcoat and most anywhere where seawater got in previously - sofar it's resisted 8 years of neglect and abuse! - It's slightly cheaper than Sikaflex and has a 3 year + shelf life /forums/images/graemlins/smile.gif
 
Thanks everyone for the extremely useful advice and tips.

The choices for sealants seem to be: polysulphide (as in Life-Caulk); polyurethane (as in Sikaflex); and modified silicone polymer (as in SABA sealtack 750 and Pro-Bond 2000) rather coyly known as MS-polymer, perhaps because silicone has got a bad name.

Experience with Sikaflex biases me towards polyurethane sealants. My local supplier of fastenings recommended a high-modulus polyurethane sealant by the name of Tremflex 40, at £5.25 plus VAT for 300ml. There's a lot to be said for having stock nearby - it enables one to deliberately under-order for both sides so that on completion of one side one knows exactly how much more is need for the second side.

The reminder about degreasing the teak is pertinent, because I would have forgotten. The link to Anglia Stainless didn't seem to work, but I found it here. The prospect of paying 60p or so per screw for a 100 odd screws is going to need a bit of reflection, especially as I've just ordered 150 stainless screws. (Feeling a little impoverished this evening having put 20 litres of petrol into my diesel car earlier today.)

The point about the epoxy standing proud as the wood wears away is a good one. Freestyle's 21 year-old teak cockpit now takes most of the wear on the black epoxy joints that are well proud of the teak. Even so, I'll probably use epoxy to fit the outer plugs on the strake (i.e. closing the hole into which the screw is countersunk) simply because I don't have enough experience of the durability of the alternatives. Easy enough to tidy up the proud bits with a sander.

Now to find trestles and a couple of willing helpers . . .
 
Quote:
closing the hole into which the screw is countersunk) simply because I don't have enough experience of the durability of the alternatives. Easy enough to tidy up the proud bits with a sander.

If you plan to use the Micro-fibres, make sure you clean off any waste before it cures, wipe with a clean rag.

This stuff is very strong and takes a lot of effort to sand.

Good luck.

Avagoodweekend......
 
You must log in or register to reply here.

Share this page

Top