Latest News: Forums Technical Mark 1 outboard bracket fitting problem

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  • #4282

    Having read the several topics on fitting the removable outboard bracket. I have run into another problem. My GRP Mark1 (S.No1200) has Polystyrene blocks fibreglassed in to the rear buoyancy tank, there is a gap between the styrene and the transom but too narrow to get a hand or spanner in to secure the bracket’s bolts. Has anyone dealt with this problem? Nick


    Alas, poor Yorick! I knew him, Horatio…..the only thing to do is to cut one side of foam out completely…try not to do it with the sun blazing down on your back as you squeeze your head and shoulders over and under the transom..the only good thing is that you can’t hear the wife in there! I did intend to replace what little buoyage such an old piece of foam would lend to the cause, but never did…now I think maybe I should. Any ideas anyone? Where’s Swiebertje when you need him? Nick, I strenghtened up the back of the transom with a piece of ply.


    Many thanks for responding, if I don’t see another solution, then I’ll chop into the styrene! I guess that a quantity of modern bubble wrap (large) contained in bags and placed in the aft buoyancy tank would make up for the missing styrene? Rgds Nick.


    From the rules:
    34.4 Positive buoyancy units of closed cell plastics foam. Shall be securely fixed within the hull of G.R.P. and composite boats, as follows (lift refers to buoyancy when submerged in fresh water):
    (a) (MK I and MKIA only) One unit providing not less than 81.65 (180 lbs) lift in the forward compartment. Not more than two units providing not less than 40.82 (90 lbs) total lift in the aft compartment.

    In plain English: anything buoyant with a total volume of about 40 liters will do. Since the new boats (World, MK-IV) use plastic cubitainers which are very similar to thin PET bottles without a cap, I see no reason why you can’t replace the foam with bottles or kegs. (Years ago we believed that bottles were unsafe because they could spring a leak).I like those red capped plastic Sauerkraut kegs that have the extra benefit of providing extreme dry storage for my valuables and sleeping bag. I got mine from a pet shop where they were sold to store pet food.

    There are some catches though:

    1. The buoyant material serves no purpose as long as the compartment is waterproof but they are the only thing preventing your boat from sinking should the compartment ever flood. There is no way to bail the boat once the compartments are flooded. The extra buoyancy only prevents the boat from sinking, no more. The extra buoyancy is important, for your crew’s safety.

    2. If, in a worst case scenario you should loose your hatch, the buoyancy material should not be allowed to escape. In other words it should be fixed inside the tank. And do not underestimate the buoyant forces involved when 40 liters are submerged.

    Back to the motor bracket, I would simply remove the material, fix the bracket and figure a way to fix any sort of buoyant material again. Think of it this way; you finally get a chance to make the aft tank more efficient in terms of storage space.

    AFAIK an American Wayfarer glassed in some empty Super sized Coke bottles (PET bottles). For extra security you could glue the caps on. From a measurer’s view I don’t care what one uses as long as there is 40 liters lift. A nice solution are two 20 liter plastic kegs fixed to the hull with parachute ribbons and spanners. That secures them in place but you can still remove them and use them for dry storage. A less sophisticated solution would be to just tie them to the boat in such a way that, should they ever escape from the compartment, they would still pull the boat up. For this you could screw some deck clips to the hog inside the tank. Simply gluing blocks of styrene directly to the GRP isn’t strong enough, you need to glass them in again.


    We have a MK1 and had this problem some years ago, we found the gap between the transom and block was enough to fit a nut so taped a metal ruler onto the spanner to make a long handled spanner, stuck nut onto the spanner with Blutack so it would’nt fall off, but once bolted up could be pulled off.
    Linda looked through the hole in the outside of the transom while I leaned inside and moved the nut around so it was in line with the hole, once she shouted it was in line I held the nut there while Linda pushed the bolt in and screwed the bolt into the nut.
    I used a stainless steel counter sunk bolt with a allan key head.
    I was luck with the position I fitted the bracket as only the two top holes of the bracket were hidden behind the block.
    I’ll send you a photo if needed
    Iain & Linda


    Ian and Linda, many thanks. I do like the extension taped to the spanner, the blue tack and your wife peering through the hole to tell you when the nut is lined up, that has to be the “British” solution. I just need to get my wife kneeling down, it’s been along time! I’m off to the dinghly park, Happy Easter, Nick.


    Here is a trick I learned from Colin.

    Thread a rope through the hole in the tank from the outside in. Then feed it through a washer and a nut. Tie a big stopper knot in the rope. Put some glue on the washer and nut and pull the rope out again. Once the washer and nut are more or less in place use a small screw driver from the outside to shift it exactly to where you want it, keeping tension on the rope all the time. Keep the rope tensioned until the glue has set. Then remove the rope and put the bolt in. Don’t put the stopper knot at the bitter end to make it easier to pull it out after the glue has set.

    And if you plan to use epoxy or Sikaflex, wrap some microwave foil around the rope and stopper knot. Epoxy and Sika don’t stick to microwave foil.


    Many thanks Swiebertje, an excellent solution which I think I will adopt. Happy Easter Nick.

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