Hedley Nicol Trimaran Plans

Discussion in 'Multihulls' started by oldsailor7, Mar 12, 2010.

  1. cavalier mk2
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    cavalier mk2 Senior Member

    Glad you are still sailing Nicols Robinglen.
    They were all designed with an inboard rudder and a main keel and ama keel/fins of differing depths. Many have been modified to just a main keel, outboard rudders etc... over the years.

    The plan thread has some drawings of most of the models scattered through it including the Buccaneer and Cavalier which can help you with ketch rig positioning if you go that route. A yawl is shown too as a Cavalier option which could be fun. I stepped the dink mast on my Vagabond MK2 stern one long broad reach day and it was fun to play with, not sure it helped much but it was entertaining.

    If you have an inboard location, size and tankage can really affect stern trim. The Buccaneer was designed for a inboard under the cockpit unlike the outboard oriented Cavalier but frequently one too big was put in there, the hulls as you know are easily driven.
     
  2. ROBINGLEN
    Joined: Jan 2012
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    Location: Port Elizabeth S.A.

    ROBINGLEN Junior Member

    Hi Cavaliermk2.
    Great to hear such a quick reply. I have an in-board engine + tank -yes, but fortunately of moderate mass - only add about 150Kgs to the aft trim, which is well within the 'reasonable load' range. The problem is that the keel (Searunner type) has actually created too much buoyancy forward of the normal centre of bouyancy, that without the weight of the removed center-plate, it causes the trim problem. This will need to compensated for. I'm working on that.
    I realise that the BUCCANNEER is still a rather rare creature in the Hedley Nicol range, and I was fortunate enough to meet Val and Ernest Haigh on TRYSTEII when she passed through South Africa many years ago.
    I discussed the ama attachment problem with him then, and I know that he had already made additional improvements to them at that point. I actually think that the final weakness was manifested from the aft attachment to the float, which I think was weak owing to the small distance between the wing attachment.and the float at that point. i.e. The failure on TRYSTEII ( and maybe others) was caused by a wave surge coming from aft and forcing the ama away from the main hull float attachment at it's weakest point by hydraulic pressure.
    However, I still think that Hedley's designs are good, and still one of the most attractive of those early trimarans. I certainly love mine.
    Find Attached picture of HUSHWING - the Buccanneer 40.
     

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  3. cavalier mk2
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    cavalier mk2 Senior Member

    Hard to tell on Tryste, it had done a lot of very overloaded miles. The ketch mizzen also puts it's chainplate load aft right there. I don't think Ernest beefed up the connectives aft, for sure some modern epoxy for glue and some uni would handle those loads better than anything he had. They had a lot of fun with that boat and it didn't let them down. Being towed by a Navy ship for hundreds of miles at 15 knots didn't break anything else with hydraulic pressure.

    You look like you have the Cavalier style cabin.

    If your keel has a aero cross section fairing added it will raise the bouyancy forward if it is full forward like a typical NACA section The original keels were like the cruising Cross keels with a straight timber section. Often that is retained as a central structure and a ply fairing added to make the aero section.

    The ketch rig mast is stepped forward of the sloop location, if yours isn't there you may want to move it if you make a rig switch before you do the keel to see how the rig weight affects the trim. The yawl uses the sloop mainmast position.

    I noticed with my boat that getting the mast rake right has a big effect on sailing trim when it kicks up. When I bought my boat the mast had been rigged with none and it tended to depress the fine ama bows, with the designed rake in the ama takes the load evenly. Every boat needs to be tuned but I noticed Hedley really did his homework in setting up the rigs for the hulls.
     
  4. ROBINGLEN
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    ROBINGLEN Junior Member

    Fuly agree with you on the chainplate story. I beefed up that area on my Cavalier.
    Both my previous tri's were ketch rigged and I raked the 36' boat's mast back about 14", and what a difference! Probably never buried the lee bow in the worst of conditions. We get some horrendous wind and seas on our South African coastline. I did not rake the 45' mast at all as it performed really well as it was, but ther was a slight tendency to scoop the water on occasion, although never felt any worries about digging in - bouyancy was good
     
  5. ROBINGLEN
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    ROBINGLEN Junior Member

    Sorry, that last message went off accidentally before I had completed my say. Further to the weakness at the aft wing attachment, the ama hatch entrance at that point does not help, as I believe it removes some of the "box" structural integrity with the deck.
    My present 'BUC' does , as you say , appear to have a NACA type keel as opposed to my previous boats which only had the skegs. It is also deeper - but only by about 100 mm (4"). It is about 1' wide in cross-section. The keel should have been longer in order to give more bouyancy for the aft section. Also being sloop rigged, has the mast-step further aft as you correctly state. The forward raised coachroof is a modification done by the builder, probably to conveniently give more headroom in the forward cabins, - a bit like the Cross 38'. I think it does add to the aesthetics rather well, besides giving better headroom below & improved access to the mast winches, etc. The "wheelhouse" and aft cabin interiors are somewhat heavily built inside, so that adds to the weight aft - a work in progress to modify.
    As to whether I will actually ever add a mizzen I'm not sure, but it would only be in the yawl position if I did. Moving the mainmast forward would be a 'schlep' with all the attendant mast-step & rig replacements needed. The fore-and-aft trim is my only issue right now, and moving the mast forward I don't feel would make much difference. The boat has approx 3" difference out of the water at the bows, but is rather noticeable. It is more about raising the stern that dropping the bows.
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    Do you know how the keel was constructed? Was the iron board offset to one side of the timber skeg keel or is it a completely different structure ?

    If the timber keel is there cutting off the fairing and redoing with a gentle curve just bringing the total width to about 6 inches will take care of the bouyancy alteration. If you don't have ama fins and aren't adding a board you'll probably want to keep the 6 inches of added depth for leeway prevention. If the fin is something very different the whole thing can be replaced too.

    One consequence of the big NACA section beyond lifting the bow is that the area adds virtual rocker to the hull which hurts high speed and the transition there, it also puts the rocker forward of the mid section.

    Keeping some ama fin has some advantages. In the world of adventure cruising it can protect the skins from grounding damage and make maintenance easier if you have to scrub or scrape etc ...

    You're right about those aft ama hatches, the openings should at least be curved in the corners. On my modified wing the main aft supports are well behind the hatches. The Cavalier and Buccaneer have higher freeboard but similar wing depth which puts a bit more cantilever load on the ama/wing connection so good comstruction is important.

    Your cabin does have that Cross 38 vibe. In defense of pilot houses they do make wet weather sailing much nicer so have fun working out the compromises. When everything gives up something but what you want is still there but not perfect unless something else goes you've arrived.
     
  7. ROBINGLEN
    Joined: Jan 2012
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    ROBINGLEN Junior Member

    Hi Cav2,
    Thanks for the ongoing correspondence.
    To answer the question on the keel. the steel drop-keel was just off-set to the inner keelson. The original outer skeg was not installed at all, and the new aero-style keel is a hollow construction with a lattice frame, which was then enclosed with a skin of 10mm ply and finally glassed. The original slot for the drop-keel has now been sealed closed at the keel base with a 19mm ply covering and glassed. The entire keel is still hollow except the slot, which has been filled with polyurethane foam.
    There are no skegs on the floats. Beaching or drying out is a bummer, 'cos like the Cross, it requires loading the one ama and the placing something the same ama to keep it slightly level, otherwise it places too much side loading on the main keel.
    My main thought now, is to simply extend the keel aft and just follow the aerofoil shape further back by about 3'. That should assist the trim a little although may slow the coming about somewhat. The remainder for trim assistance will be the need to remove some of the 'deadweight' furnishings from the stern interior.
    I LOVE my wheelhouse, as it really does give that extra comfort and protection from weather - besides the fact that it gives the feeling of an extra cabin. It's big disadvantage is the creating of a communication problem to anyone out on the fore-deck area. It also slows progress when needing transit quickly from one side to the other via the cockpit. This wheelhouse is still totally enclosed but I aim to rectify that by opening it up and placing removeable side-awnings in place. Like you say, can't win 'em all, it's always compromises.
     

  8. cavalier mk2
    Joined: Mar 2010
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    cavalier mk2 Senior Member

    If you extend the keel aft you do have the advantage of keeping the extra bouyancy to help with load, the taper means it isn't as much as the front of course. I'd think you don't want it any longer than a Cavalier keel to preserve the balance with the rig.

    It sounds like you have everything well in hand. Since you are on Nicol number 3 you've aquired great experience in learning what works. For sure getting out the heavy stuff will do the most good. If the windows are glass huge weight savings can be had by going to plexiglass, I posted some how to things I learned in the construction section when I did mine.

    I still have projects going on mine, new stove and boom was all I had time for this year. I made a sled for the out board a couple years ago that has worked out great which retracts into a opening in the port quarter deck area. I promised Corley I'd post some pics so I'll have to make the time. My cockpit was built nonstock to accommodate a hard dodger/ pilot house so I had to be creative in working with the layout. The motor winds up next to the forward end of the stern cabin. Hedley had specified a bracket in there to take the motor on races or offshore but I doubt many people bothered. Getting the weight off the transom is an improvement and it opened up the stern for a eventual stern/ rudder upgrade.
     
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