17/02/2021 at 4:21 pm #21255
I’m about to paint the hull and need to ascertain the position of the keel band flow diverters ( for want of another description ) at the fore and aft end of the centre board slot. I’ve just taken delivery of 3mtrs of folded reinforced sailcloth which I believe when fixed into position overlap 4mm at the centreline. Iv’e also seen on another dinghy class website that the sailcloth can be cut at an angle to assist drainage of the centreboard box. I have not seen another GP14 in the flesh so please excuse my ignorance in these matters, never to old to learn.
(1) Could anyone please advise where the flow diverters are fixed and where the gasket starts and finishes including any angled cuts.
(2) Is it best to punch out the sailcloth where the fixings pass through so save thread tearing.
(3) I take it the Gasket needs periodic replacement. If so what’s best way to waterproof the fixing screws yet allow them to be removable.
Thanking you in advance, Windy.
17/02/2021 at 6:01 pm #21258Oliver ShawModerator
The first thing is a check on Class Rules, from which the relevant points seem to be:
Rule 3.5 Metal keel and stem bands shall be of segmental section with a size tolerance of 16 x 3mm to 19 x 5mm.
Rule 14.1 The following permitted fittings are optional and must not be substantially in excess of their intended function in either weight or size. … … (cc) Centreboard slot flaps
So, subject to limits on dimensions of the keel band and the slot flap, the details of everything that you intend to do are all optional!
Do I assume that this is a refurbishment (or even restoration) of a boat which does not currently have these fittings? I ask because if you do have existing fittings there is a lot to be said for staying with the same arrangement, even if the fittings themselves need replacement, unless you have a specific reason for wanting to alter the arrangement.
I have found two photos on the GP14 Online Community site, which were posted for other reasons but which do nonethless show the arrangement on those particular boats. https://groups.io/g/GP14onlinecommunity/photo/245159/9?p=Created,,,20,1,0,0 and https://groups.io/g/GP14onlinecommunity/photo/246775/12?p=Created,,,20,1,0,0 You might have to join the Group before you can access them, but it is free, and you would be welcome, and might find us useful. We are independent of the Class Association but maintain very warm reciprocal relations (and we have from time to time discussed merging our respective operations).
Now to address your specific queries:
(1) Normal practice is to have Y-pieces or triangular pieces (shapes differ) in the keelband to make the transition between a single keelband forward and abaft the slot and a twin keelband alongside the slot, one band each side of the slot. These should not encroach upon the slot itself, but should otherwise be as close as possible to the slot.
The slot gasket (sailcloth or other material) should be sandwiched between the keel and the keelband either side of the slot, and may extend under the Y-pieces.
(2) It probably is a good idea to punch out the boles in the gasket where the screws are going to pass; but I would normally do it in situ, by means of a bradawl or similar tool. I don’t think it needs an actual hole punch; but if you happen to have one and can measure up accurately enough then by all means use it.
(3) If you grease the fixing screws with Vaseline or similar, or alternatively put a dab of (non-setting) mastic on them before inserting them you should find that this prevents water ingress via the screws and also helps with future removal. Avoid brass screws! (Use either stainless steel or bronze; the former are readily obtainable from almost any marine chandler (and in a limited range of sizes from a few DIY shops), bronze are usually available only from specialists, and I myself use Classic Marine when I need such items.)
> Iv’e also seen on another dinghy class website that the sailcloth can be cut at an angle to assist drainage of the centreboard box.
Sorry, I can’t help there. But others may be able to.
Hope this helps,
17/02/2021 at 9:18 pm #21259
Thank you for replying. I should have made it clear that this is my new build and instead of bombarding the kit supplier with questions I thought it’s about time I asked a wider knowledge base. I’ll try and add a couple of pictures to explain my questions.
Point (1) I’ve produced the “Y” pieces and want to fix them close to the slot, but in doing so the double legs run down the side of the slot 30mm or so meaning the Gasket would start back from the slot ( surly not good) as in Pic.1 You mention extending the gasket under the “Y” pieces but if these are glued and painted first I can’t see how. Pic.2 shows the “Y” piece places further forward meaning the removable Gasket will cover the slot completely. Is this the best option?
Point (2) Thank you and noted.
Point (3) I will be using A4 stainless screws and will do as you say with regards to sealing them, thank you.
I will look at joining the online community soon so as to access the photos you’ve kindly looked out for me.
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18/02/2021 at 10:37 pm #21274Oliver ShawModerator
That is a very nicely made Y-piece in hardwood; I have never seen them in wood previously, always in metal. My one concern is that the wood will not take abrasion as kindly as metal will, but you would want to protect the bottom from abrasion anyway. This basically comes down to appropriate care in launching, and beaching, and recovering the boat onto her launching trolley; just be aware of this small area of alight vulnerability.
Given that, I think I would approach the problem by painting the hull (or varnishing, if you prefer) before fitting any of the keelband. That is best practice anyway. At the same time paint (or varnish) those Y-pieces.
Then I would lay the slot gasket the full length, including the full length of the Y-pieces, preferably tensioning it slightly as you fit it, as Steve has described.
Finally trim off the excess from the outside of the Y-pieces (and the outside of the keelband along the slot).
18/02/2021 at 12:09 pm #21263steve13003Participant
Not much to add to Oliver’s comments but it is normal to bring the new slot gasket forward to be under the forward Y fairing, trim off any excess material after screwing down. To get the best fit and performance I normally tension the new slot gasket by having eyelets aft of the end of the slot through which you can pass a rope to the transom keeping the gasket tight while you screw down the rubbing bands to hold it in place, make the screw holes as described by Oliver once tensioned. Make sure that screws in the rubbing band are completely within the countersink recesses – file down the heads if necessary so no sharp exposed edges to catch when sliding you boat on and off the trolley .
18/02/2021 at 3:00 pm #21273
Thanks for that advise re the tensioning and proud screws. Still can’t get my head around the gasket being under the “Y” fairing. The dinghy gets fully painted before the Gasket is fitted so are you saying the front “Y” fairing is fitted after the painting or do I craft a slot in the rear edge of the “Y” fairing to slip the Gasket into, slightly confused. Can you confirm the gasket overlaps at the centre is 4mm or there about.
19/02/2021 at 8:20 am #21275ChrisParticipant
All the advice above is good 🙂
Last thing from me is that most people think its the back of the gasket that does all the work and affects performance (if this is important), it’s actually the front that does the most and its the front that causes the water to pour in over the top of the case if its either wrong or worn out.
19/02/2021 at 11:31 am #21278steve13003Participant
Yes the gasket should overlap by 4mm or so if using a sail cloth version, some now use a Mylar slot gasket which is fitted as a single piece stuck down with Thixofix glue and held under the rubbing bands and then slit after fitting. Your wooden Y fairings are unique, but I would still take the gasket material under the Y fairings to the point where the Y is a single, to make sure no step between the Y fairing and the alloy rubbing strips, paint or varnish the hull before fitting the slot gasket, paint varnish the Y fairings before fitting.
19/02/2021 at 7:53 pm #21281
Thank You gentlemen for all your help, you’ve given me some good advice which I will act upon shortly. I’ll post a picture when completed for all interested.
Kind regards Windychippy
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