Newbie building questions

Discussion in 'Multihulls' started by grey487, May 13, 2013.

  1. cavalier mk2
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    cavalier mk2 Senior Member

    There is a difference between a surface riding ama like one of the 200+% ama boats and one that immerses some with the load. I don't think the former makes for a good cruising boat because of the ride and shock loads. The latter is best double ended imho for less turbulence. Flying the main hull isn't good for cruising, getting some feedback about time to reef is. In either case having the ama compensate for the main hull attitude is going to cause more drag.
     
  2. Corley
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    Corley epoxy coated

    I'm not sure I'd be too concerned about a bit of extra transom drag when the floats immersed that far on a 200% ama boat by definition the main hull would be nearly lifted out at that point which should provide a net reduction in drag anyway. I agree a rare circumstance to lift the main hull while cruising but I wouldn't mind a bit of extra volume in the transom just in case I was caught out by a gust.
     
  3. cavalier mk2
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    cavalier mk2 Senior Member

    For cruising I don't like the possibility of the wide transom holding the ama bow down when running down a wave. If the amas are long enough there should be enough area aft to protect against a backwards trip going up a wave so I'll take the stern that reduces the tendency to pitchpole. For a racer that flies the main hull the transom makes sense as the ama is taking the place of the main hull but that isn't cruising by most definitions.
     
  4. Corley
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    Corley epoxy coated

    Your making the assumption that the extra volume in the float transom is unbalanced relative to the rest of the float volume distribution I'd prefer the extra volume as long as it's balanced with sufficient reserve buoyancy elsewhere in the float.

    Sorry to the OP as our little OT debate is not helping with your initial question.
     
  5. John Perry
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    John Perry Senior Member

    Returning to the subject of the original post, I wonder if the OP would be interested in the non-commercial design project that I presented in the following post:

    http://www.boatdesign.net/forums/multihulls/post-your-design-ideas-37103-8.html#post555089

    This catamaran is designed to be demountable to permit occasional land transport and it provides a covered watchkeeping/steering position, both requirements of the OP. On the other hand it is smaller than the OP is thinking of and may not be sufficiently spacious below decks.

    I have done a bit more design work on this project over the past winter months and have drawn an alternative arrangement for the outboard motors which I think would be an improvement, otherwise the concept and general arrangement remain unchanged. I hope to soon be away sailing for the summer in our present boat so am unlikely to give much more thought to this project until next winter.

    I have not decided whether to leave this as a design project or progress to a building project, but if I do build it I had wondered whether one or more other people would be interested in it, in which case perhaps there would be a possibility of some collaboration with regard to sharing information regarding materials/equipment suppliers, design improvements, building tips, correction of design errors (it would be amazing if there were none!) etc. Also, if two or more builders were in the same geographic area there might be a possible saving by using computer controlled cutting to produce parts for more than one boat under a single contract.
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    We'll have to disagree Corely, for the OPs cruising question the full transom will give a harsher ride. No matter the volume distribution it will also lift more than a slender stern. Less/more gentle motion when cruising is a good thing.

    Back to the OP if you like Richard's boats (and it is hard not to) or other non demountable builds and you just have to move it once it might be worth considering a longer site assembly to get the boat you really want.
     
  7. Richard Woods
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    Richard Woods Woods Designs

    Thank you

    I'm not sure, but I don't think a full cabin trimaran like a Horstman can be built in sections inland and assembled by the water in a week? A bolt together Romany could though

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  8. grey487
    Joined: May 2013
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    grey487 New Member

    The previous posts definitely went over my head, but all of you led me toward the answers I needed. So thank you! It sounds as if most of you agree I would get a better ride from a cat. Given our need for such I'm fairly certain that's the direction I will end up taking provided I can figure out the logistics on reaching the water with it.
    Richard, in the photo you posted, it appears the boat is nearly 20 feet high. If that's the case, it would never make it under the bridges along the highways here. However, after looking at the blog of the couple who are building your Romney design, it appears that I could build the hulls and cockpit and keep them separate until I get to the water. Do you have a better photo of the interior layout of the Romney or would I need to purchase study plans for that?
     
  9. CutOnce

    CutOnce Previous Member

    Can't resist this.

    The Romney design includes a car elevator and a bridge deck caviar refrigerator. It is capable of over land travel, but it needs a charter airplane to move it and it's Fox News press crew.. The only offshore travel it does is to banking establishments in the Cayman Islands. It isn't one of Richard Wood's boats.

    Richard's design is the Romany. Much more appropriate for your requirements.

    --
    CutOnce
     
  10. cavalier mk2
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    cavalier mk2 Senior Member

    The wing deck tris would take longer to assemble. And the fat stern, plump ama, teeth rattling, me too gizmos by people like hughes would be a hard ride. (Sorry Corely, you're not building yours for cruising.)
     
  11. Corley
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    Corley epoxy coated

    I don't think you would build a cat for the better ride per se but for cruising the advantage really is payload. Since you have two hulls that are immersed all the time you can carry more gear (within reason). I think that is the most important consideration from a cruising perspective when you see how many catamarans get around dragging their transoms due to overloading it gives an appreciation of how important that criteria is. We had one speaker at one of our club meetings who when giving his speech on cruising noted "one of the prime things you should consider for multihull cruising is how much equipment, stores, fuel, toys and general junk you want to take relative to the location you want to cruise and the duration and work from there when looking at suitable designs", sound advice.

    Trimarans that are geared to performance cruising are even more weight sensitive. Cavalier and I disagree on some points but are both trimaran enthusiasts and we still think they are a valid choice they just have to fit in with your own requirements and lifestyle.

    Tony Grainger's write up about trimarans in the modern context is I feel a good description of what they offer.

    http://www.rocketfactorytrimarans.com/about-the-rockets/about-trimarans/
     
  12. cavalier mk2
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    cavalier mk2 Senior Member

    Yes all joking aside I like some of Kurt's boats. I go sailing to sail and do like tris for cruising, the approach has merit for many. Trimarans as a rule of thumb have to be longer to have the same payload as a cat. 1 load bearing hull versus 2. Off the top of my head the only cruising tris I can think of that are as easy to build as Romany and can be assembled at the launching site are Marples Seaclipper series. Longer can mean more speed but also more money for things like building,docking and haulouts.

    For any multihull the more that can be left behind the better off you are. Figure out things you really want to bring and have on board then buy a book on how to live without those things, it is cheaper and lighter!
     
  13. Richard Woods
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    Richard Woods Woods Designs

    Thank you for your continuing interest in my designs

    The Banshee in the photo was actually under 17ft high as that is the minimum height power and phone lines must be in the UK. There were no bridges to go under on the route we took (and remember about 40 similar multihulls all later went the same way). The boat itself was 20ft wide

    If you want to see better photos then, for now, I suggest you look at the Romany Cruising articles which I wrote about our trips to the Bahamas in our own Romany. There are links on my Useful Articles page

    http://sailingcatamarans.com/index.php/articles/9-cruising-articles

    I'll post more on the Romany page later, as I see there aren't any there.

    I would also suggest that you email me direct to talk about a specific design rather than doing so here

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  14. catsketcher
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    catsketcher Senior Member

    Don't build a tri

    I started my multihull sailing life as a dyed in the wool tri man. I had a Nugget and a Twiggy that were seminal boats for me. I had drawn the perfect cruising tri (for my family and me) and it took me 12 months of tweaking. All my friends and boatbuilders I consulted said "Build a cat you idiot". I would fire back "Cats are terrible - they don't sail properly, they lack feel, you can't see from the helm - I am building a tri".

    Then one night after trying for hours to get my boys some extra room in their cabin and going through the hundredth iteration of the design spiral I thought why not just do the accommodation plan for a similar sized cat. After 5 minutes it was apparent I could get about 2 and a half times as much usuable room as a tri. I built Kankama and she was a fab cruiser and still is.

    Building a tri is not good in the money sense. With boats down in value tris have fallen right down. Unless you want to lose lots of money I would buy rather than build a tri. As for buying, tris make huge sense as you can get a 40 footer (I have always loved Searunners) for less than $80 000 which is much cheaper than a cat. For two people a good old tri makes sense.

    If you want to build then you have to do a cat as you will get bummed out by the process and need to ensure you are doing something sensible. Unless you are going to have your boat hold value a tri will cause angst as you see all your money go into a pit you will never see returned. It will take all your time and effort. It would be nice to see it not take all your money for only half a return.

    Have you double checked all possible routes to water including rivers? If so then consider talking to clever designers WHO HAVE BUILT LOTS OF THEIR OWN BOATS as they will be able to amend some designs to allow you to build the hulls - with all of their accomdation fitout, the beams, cockpit, cabin top, rudders, winch pads etc separately. You will pay more to do it this way and then put her together in a shed by a river where

    - hulls and beams are joined
    - prefab bridgdeck bottom is joined to hulls
    - premade cabin furniture is installed
    -premade cockpit is dropped in
    - fairing of joins is completed

    You push her in

    Maybe 2-3 months with a good helper and a well done computer cut build.

    Easier to find that river

    cheers

    Phil
     

  15. cavalier mk2
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    cavalier mk2 Senior Member

    Very sensible Phil....of course if you add a dash of adventure and hint of romance, along with that better feel trimarans look worth it too. I'd like to make a Newick just because it's so beautiful but keep a scow sketch in case I ever have to be really practical. Thank goodness for the Nicol....
     
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