Replacing wooden rubbing strake

[Guest]

I need to replace a long section of the two-by-one inch wooden rubbing strake bolted through the grp hull.

Two half-inch laminations, glued with epoxy seems a good idea but I am puzzled as to how to proceed.

I want to end up with a glued curved laminated section which I can unbolt for the final shaping, sanding and bed in with sealant. I think I can bolt one layer to the well curved hull but doubt that I can bolt and bend two layers. Needless to say I don't want any trapped bolts.

Someone described the sequence he went through to achieve this result on his boat but I forget what is is......!



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[Avocet]

I did mine last year. It is a teak "L" section with the capping part (the one facing upwards) about 1.5" wide and the vertical part on the side of the hull about 1.75". Each "leg" was about 0.5" thick. I was quite surprised at how easy it was to bend this section "cold" round the hull. That said, our boat is very narrow (7'6" beam and 27' long). Each strip was made of three pieces scarf jointed together with a 6:1 scarf and epoxy. One of the joints "popped" open but that's because it just landed with its end over a screw hole. It was easily fixed but if I was doing it again I think I'd go for an 8:1 scarf.

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[tillergirl]

It will be possible to bend 1 inch timber - I replaced part of my beam shelf (that's the inner timber at the top of the inside of the hull) and that was one and three quarter inch thick. I note that you are talking about a 'long section' and joining the new to the old will need some care (but is not impossible). I got the timber ready first - if you have to join two or more lengths, scarf them at 8 to 1 (as the other post says) and glue (I'd use epoxy). Use as many clamps on the joint as possible. Once cured, we pre-bent the timber using a jig in the right shape. Clamping frequently supported the timber during the bending and made it easier to handle. As we had other work to do we left the bent timber in position on the jig for a month - not necessary abut it seemed to help. You probably would not want to do it that long but a couple of weeks would help, but I admit it is probably not necessary at all.

Your new section has got to be scarfed into the old. You don't say how long the section is or whether its a middle piece or not. I would seriously think about whether cutting the scarfs and aligning is better than replacing the lot.

I assume you had a flat section on the hull to attach this. If so I would get the final shaping and sanding etc of the exterior three sides done before fitting. That will give you the correct shape when fitted That leaves you with the shape of the hull, the sheer and twist to deal with! If the hull is flat where you are to attach the rubbing strake, this should go fine. As many fastenings as possible will ease the process and avoid trapped fastenings. A couple of mates will be really handy. Are you able to clamp up the strake before fastening. If so do so with as many clamps as you can borrow.

If you are doing a middle section, the real problem will be getting the last end into shape which is why you should think about doing the whole lot. Then you can keep the new timber a little over length, start at the bow, once fastened there, curve it round the hull following the sheer (which will require your mates to impart some twist probably) and the overlength piece will enable you to bring it in at the stern. Nice and easy, as much support as possible and fastened little by little as you go.

Good luck

Just had a thought - were you using two pieces to hide the fastening bolts? If so provided the bolts are not too big, think about countersinking and plugging. You won't see the bolts then and you can use one piece of timber.
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by tillergirl on 08/06/2003 11:07 (server time).</FONT></P>