Latest News: Forums Technical MkII SD Drainage Tubes

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  • #4375
    davehansen
    Member

    Hello,

    I have a 1985 Mores MK2 SD, which I am considering modifying to have drainage tubes through the stern tank.

    I have read about the difficulty in righting an SD after a capsise, where the air in floor compartment makes the boat unstable as the water in the boat surges from side to side with the struggling crew. Although it feels a very stable boat to sail I, would rather not worry about capsising and being unable to recover the boat, so inserting drainage tubes seems a good idea.

    If anyone can offer any advice as to how best to go about this or has any photos thay can share with me of this modification, I would appreciate it.

    I had thought about using white pvc drainpipes, epoxied in position with some marine ply supporting discs.

    Thanks

    Regards

    Dave

    #10492
    Colin Parkstone
    Participant

    Its getting the height right of the tubes and the sealing of them in the bulkhead faces thats the important bit.
    Then the sealing of the tubes as well so water cannot come back in the boat. Think the job from start to finish before you start, make sure you can get at all the points that will need a good seal. CP

    #10496
    Dave Barker
    Keymaster

    Are they just straightforward tubes, Colin, or is there a one-way flap/valve? I’m finding the whole thing difficult to envisage, never having had a proper look at an SD set up in this way…

    #10497
    davehansen
    Member

    @Dave Barker wrote:

    Are they just straightforward tubes, Colin, or is there a one-way flap/valve? I’m finding the whole thing difficult to envisage, never having had a proper look at an SD set up in this way…

    I was planning to have straight through white drain pipes (70mm). First cut out some O shapes in thick marine ply. Expoxy these to the inside of the tank, perhaps using stainless screws aswell. Insert the drainpipe which is a tight fit, then expoy using webbing cloth. then Gel-coat over to make it look tidy.

    The pipes would be positioned so they sit just above the water line (with some weight in the boat), and positioned near the floor on the inside. I would have to do some tests with a spirit level.

    I have had a look for bungs and drainage tube set-ups for boats, but everything I have found is too small a diameter. I would probably look at making up some transom flaps, and use bungs in the inside of the boat. the bungs could be quickly removed when capsised.

    I was at Hayling island YC in the autumn and noticed an SD with drainage tubes, they were taped over. I didn’t lift the cover to have a more detailed inpection, I wish I had now though.

    Dave

    #10500
    Colin Parkstone
    Participant

    Anyone got a picture of the tubes !!!
    I have not seen one for some times but i would say that 70mm sounds a bit big, what if they land up to big?
    How about starting a bit smaller, say 50mm and I remember a thread on here that talked about how they let water in to much and needed to be covered when not in use.
    Tread with care!!

    #10502
    Davdor7038
    Member

    Found this on the WIT site under class rules. Rule 15.7

    15.7 (Mark IISD and Mark III only). Drain tube outlet ports in transom. Maximum number permitted shall be two. Maximum diameter of each 112mm (4.3/8”). Outlet ports shall be connected with the cockpit in a watertight manner by tubes of maximum diameter 112mm (4.3/8”). Regards, Davdor

    #10511
    davehansen
    Member

    Hi Davdor,

    Thanks for the reply. I had read some articles on the WIT site and they are useful. The north American Abbot boat appears to have the same under floor bouyancy arrangement.

    I would still like to see how someone has done this job on a SD though.

    Dave

    #10515
    Dave Bevan
    Member

    Hi Dave. Sounds like you’re hoping for a SD owner with drain tubes to come along with some photo’s and measurements. There was one at Grafham water centre when we did our RYA level 3, don’t know if they still have it (it was about 15 years ago 😯 ). They must have had a standard-sized tube because they used expanding drainage plugs to block them which seem to come in 100 and 150mm diameters.

    Give Ian Porter a call. He will should be able to explain how they built their SD’s, and he’s probably seen a few Moores boats in his time too.

    #10685
    davehansen
    Member

    I was at chew Vallyy Lake the other week and had a look aound the boat park, there were many wayfarers parked up. I noticed an SD which had drainge tubes cut into the transom. The pipes had openings of approx 100mm and exited the transom at both port and starboard sides with the bottom of the holes paralell with the chine angle.
    On the inside the pipe openings were nearly flush with the floor in the corners under the benches.
    There were no bungs or transom flaps so I assume that this boat was mainly used for racing.
    It was a useful viewing.

    Dave

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