Latest News: Forums Technical Converting to centre sheeting

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  • #3713

    I’m going to convert my Moores Mk 2 to centre sheeting. The attached pic (not my boat obviously) shows a raised level mounting area on the centreboard case behind the thwart upon which the swivel jammer and block are mounted. I note this mount platform is pretty universal to both woodies and grp boats. My boat has this feature and currently has a compass mount screwed into it.

    This is obviously the right place for the block, but I don’t know if it’s suitable to fit using screws, or whether it should be bolted through. Anyone know what material is inside the fibreglass moulding and how a bolt through option could be achieved given that there is no easy access that I can find beneath.

    Any help much appreciated


    @David Smethurst wrote:

    The attached pic (not my boat obviously)

    Obviously, its a picture of Swiebertje. the last Wayfarer (+S) ever build!

    On Swiebertje the block and jammer are simply screwed with long, 5mm self tapping screws. AFAIK there is a piece of hardwood soaked with resin inside the triangle. Meanwhile the Ronstan swivel base, cleat and ratchet block have been replaced by Harken gear. Perhaps it is personal but I like the Harken solution much better.

    On my old MK2 (see avatar) I made a plywood box (7 mm plywood) that fitted over the sides of the CB-case. Four small 4 mm bolts went horizontally through the flanges of the box and through the sides of the CB-case. I used four wing nuts behind the flanges by holding the wing nuts (one at a time) between my stretched middle and index fingers while the (countersunk) bolt was turned by a screwdriver. The construction is also easy to remove for winter maintenance. Because the bolts are horizontally the whole construction is very strong and stresses are well distributed over the CB-case’s GRP.

    By fitting it with flanges over the sides, the box was obviously wider then the width of the CB-case and much larger then the triangle shown in the picture of Swiebertje. I used the extra area on the top of the box for two spinnaker control line cleats. These control lines went over the top of the CB-case and straight through the thwart, using four SS-lined bushings.

    Because the box is removable the main sheet block and jammer can be simply bolted to the top box (obviously before bolting it to the CB-case). I used some large washers to distribute the load. The jammer is also easy to remove in case the box needs a little TLC.

    On other MK2’s I have seen a massive block used:

    As far as I can tell it is almost as wide as the top of the CB-case, much wider then the little triangle shown in the picture of Swiebertje. AFAIK it is screwed to the CB case using self tapping screws, upside down through the sides of the top the CB case, through the flanges alongside the actual CB-case (center part). The block and jammer are then screwed in to the block with self tappers. Perhaps someone who really uses such a wooden block can comment?

    BTW, the picture comes from , a little web-shop specializing in typical Wayfarer parts, owned by Thomas Raun Petersen, the SWS secretary. Thomas carries this block as a stock article.


    I think it’s highly likely there is at least a plywood pad under that into which you can screw directly. I would sugest a trial hole (perhaps where you might drill for a screw in any event) and examine the drill bit for wood fragments. If there is wood you can assume it was put there for a reason.

    Colin Parkstone

    When you drill into this block you will find wood/plywood.

    Sometimes this area can have voids in the glass,wood and bonding agent.

    I suggest that if you find a void you fill it with resin or epoxy before you fix any fittings as this is going to take alot of strain.

    When it is dry,drill the pilot holes for the screws you are useing AND then countersink the pilot holes to the same width as the screw shank.

    What this does is stops the thread of the self tapping screw from lifting the gel around the screw out,Horrid if you can see it showing outside the fitting.

    Then, fix the screws in with Araldite or Epoxy for a firm job.

    CP 🙂

    Dave Barker

    I recommend always using a countersink before drilling anything but the smallest diameter hole through or into GRP. This in effect safely grinds away a circle which you can make the right diameter for the actual hole that you want to drill (in fact just slightly oversized is best).

    If you go straight in with a drill anything more than about 2-3mm diameter, the flutes on the drill bit tend to ‘grab’ the gelcoat and break chunks of it off before you have time to stop the drill.

    If you can be bothered (and why not?), drill a pilot of say 2mm diameter to guide the countersink, then use the countersink, then drill the intended hole(s), including the clearance hole mentioned by Colin, if applicable, for which you can now safely use a normal drill bit, having already created an adequate countersunk hole.

    In an emergency you can get something like the same effect by using your drill in reverse gear, i.e. with a (full-sized) drill bit rotating anticlockwise.


    Thanks all for the comprehensive info. Fancy getting a reply from the pictured boat’s owner. I cut it out of a page on either the Canada or USA site without really knowing it’s origin. It was described as the “Rolls Royce of set-ups”. Swiebertje is a pretty well known boat I guess. As a newcomer I have spotted the name dotted around various sites.

    Anyway, Following your advice I have removed the compass mount that is currently fitted there, and there is clearly timber inside the moulded GRP. Thanks for all the drilling advice. I’ll go for the screwed option initially as the epoxy assisted methods sound pretty robust. I’ve been loitering in the dinghy park and all the versions I’ve checked out appear to be screwed. The wooden wedge method bolted through the wider section of the c/b casing seems like a bombproof solution if I run into trouble. I guess the trick is packing the underside properly to spread load on the grp. Thanks again.


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