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*2021 AND SOME EVENTS ARE BEING PROPOSED. Keep them coming and let us know the details! (


Model Sub Weekend, 28th, 29th August. Bluewater Parkway, Greenhithe, DA9 9

Bournville Sub Day. Sept 2021 Nothing heard since Spring. Maybe cancelled?

Barrow in Furness Regatta and Sub day. Nothing planned this year but Guests always welcome on a Sunday morning.

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    What would be the right trim level


    Posts : 20
    Join date : 2021-04-22

    What would be the right trim level  Empty What would be the right trim level

    Post  Michaelc Fri May 28, 2021 11:14 am

    Hi chaps. Today I started to work on my drenell T class sub. First time in water. This is just the bear hull with props in place. The hull fills water and goes to the bottom like a stone. So here are my questions.
    1. Should the hull itself have negative buoyancy when in the bear state or should it sink.
    2. How low should the hull sit in the water when WTC cylinder is included.
    Thanks, Michael
    AMS Forum Owner

    Posts : 312
    Join date : 2011-09-02
    Age : 61
    Location : Las Vegas, Nevada - USA

    What would be the right trim level  Empty Re: What would be the right trim level

    Post  salmon Fri May 28, 2021 4:32 pm

    Just the bare hull? Do you have a ballast system installed?

    If you have a ballast system, and what type, will make the best advice if it should be negative buoyant or positive (and add personal preference into the mix). I have gas based systems that I keep positive buoyant (so with tanks flooded about an inch or about 25mm above the surface).
    If it is just a empty hull, then yes it will sink as the material it is made from is heavier than water (~ 1 to 1.7 times I have been told). If you are doing this to figure what size ballast tank you need to lift it up, Then you add closed cell foam to the sides (below waterline) or beneath until you get the correct waterline. Then add a percentage just as a safety and to compensate for add ons.

    Did this help or did I completely miss answering your question?


    If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

    david f likes this post


    Posts : 20
    Join date : 2021-04-22

    What would be the right trim level  Empty Thanks

    Post  Michaelc Fri May 28, 2021 9:03 pm

    Thanks. Will play with the foam tomorrow.

    david f likes this post

      Current date/time is Sun Sep 19, 2021 11:54 am