Blending designs ( Tomcat, Waller )

Discussion in 'Multihulls' started by saltifinch, Mar 26, 2016.

  1. saltifinch
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    saltifinch Junior Member

    I would appreciate some opinions on merging some designs into one boat. And hopefully my reasons make sense. If you have any thoughts about the layout, please feel free to share!

    I need plans to start building, and the Waller Coral Cove 31 is perfect, great price, great design. Now to list the things I would like to change, and where I got the inspiration.

    I want 6ft of standing room in the saloon, heading down to the hulls, and I think the Tomcat 970 does a great job of this, by creating the doghouse. It offers protection and good visibility for the pilot also. Lowered headroom for the seating area is a great compromise for windage.

    I also really like the layout of the boat, 3 double beds, a dressing area for the master suite ( great for liveaboard ), a walkthru washroom in the port hull, and a long galley in the starboard hull.

    However, I dislike having no walking space around the edge of the boat, making access to the bow more challenging.

    Here's my solution. Start with the Waller design. Extend the width of the saloon into the hulls, allowing 2 feet of walking space on both hulls, while shortening the length of the saloon, allowing room for a double bunk forward.

    I would also like to run 2 outboards, possibly 9.9hp, using the Bob Oram style mounts.

    Any problems/suggestions? If it would help, I can draw up some plans to give a better idea of what I'm saying.
     
  2. catsketcher
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    catsketcher Senior Member

    Email Waller and talk to him. He may do the changes you want but with an understanding of why.

    There is a thing called the design spiral. Almost everything you do will affect everything else. It is very hard to get standing headroom on this length cat.

    Extra time spent getting the design right will more than pay for itself later on. Get a holistic design worked out before you start the build.

    My fav short cat is Richard Woods Eclipse. If you think you like the Waller have a look at Richards design and explain to yourself why you shouldn't go this route or another properly designed cat of this length. If it is money you are kidding yourself. If you want three doubles and lots of room it is going to cost. Shortening the boat will not magically make it cheaper. Length doesn't cost much compared to the mistakes you will incur from a hybrid design.

    Also try http://easycatamarans.com/website_004.htm for a look at the Easy 32. You will see no permanent 3rd double but you can get that by dropping the table. You won't be able to live three couples in this boat - you will end up hating each other so two doubles should be fine with an extra for overflow.

    cheers

    Phil
     
  3. saltifinch
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    saltifinch Junior Member

    I've spent a lot of time looking at those designs you mentioned, and while they're excellent boats, I find their design antiquated, some wasted space, and layouts that don't incorporate modern concepts very well. And I don't feel their exterior looks to be very appealing. I feel that with some extra work, they could look a lot sharper, with a lot higher value.

    I'm not a fan of the mast through the dining room table, as in the Eclipse.

    But, before I go mouthing off people who've been in the business for decades, I should really draw up my own designs. I'm a welder, fabricating is no mystery to me. But the structural issues involving boats are, and that's why I need plans. You are probably right, messaging Waller is probably a good idea.
     
  4. saltifinch
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    saltifinch Junior Member

    Any opinions on walkthrough bathrooms in the middle of the boat? If it's just too crowded in a hull this size, I may just place it in the Starboard bow. Although I hate having the kitchen and head so close to each other.
     
  5. Steve W
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    Steve W Senior Member

    If you look at the Gemini cats they have a layout that you may like. Crappy build but good layout including a narrow sidedeck that does allow passage forward but I think most folk go over but it does make docking easier. Roger Simpson used to have a nice design about this size, I think the plans may still be available from Boatcraft.
     
  6. saltifinch
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    saltifinch Junior Member

    That's why I'm building. Cheaper and better quality. At least in my mind. I love building stuff haha.
     
  7. jamez
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    jamez Senior Member

    Have you checked out the Boatcraft Pacific 9.5? Kind of similar looking to the Tomcat and already has the dodger, 6' headroom in the saloon and narrow side decks. Was a write up in April 2005 Multihull World.

    I corresponded with Mike a few years ago about his 25 foot cat design and found him very helpful. I quite like his cc 31, but aesthetically find the bow a bit too raked for my taste. I think I'd prefer a smaller version of his 11 metre..........

    Ray Kendrick also had a nice 9.5 meter bridge deck cat on his website a few (actually probably 10:) years ago but I don't think its now part of his range.
     
  8. saltifinch
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    saltifinch Junior Member

    Here's a quick drawing I put together this afternoon. Any suggestions? I think it will work well.
     

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  9. catsketcher
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    catsketcher Senior Member

    I have designed two boats and know a little about how hard it is to get all of the parts of the boat right. For instance you cannot move the saloon bulkhead to get a double in front. It is the major bulkhead in the boat. It can't be moved without a huge redesign.

    I really think you need to learn a bit more about design before building if you want to change parts. You cannot pull apart one aspect without pulling apart another.

    Get on some boats and sail them and live on them. What you see as wasted space could be good room for fenders and swim fins. Both the Easy and the Eclipse were designed by builders who have sailed thousands of miles, lived on board for years and built tens of boats. You have to be incredibly smart to do it better than them.
     
  10. catsketcher
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    catsketcher Senior Member

    That is no design

    Salt - the accommodation plan you drew can't work. You need to understand you are designing a sailing boat with lots of important factors before you draw accommodation.

    The main bulkhead is far forward. The mast will be stepped on this bulkhead. So you now have a boat with a very small foretriangle and large main. Not usual. This will have an impact on the LCB of the boat as the CLR will be further forward. Have you changed the LCB of the hulls?

    Look at the fore berth. Assume it has enough room over it to sit up - about 900mm minimum. You have to drop the bridgedeck down 900 mm almost vertically from its front edge to get the depth. Very bad news - because you have pushed the bridgedeck forward the front will now bang into waves when you pitch.

    Look, do what you like, build whatever you want but I see a world of pain and a real pig of a boat unless you pay someone to do the design spiral for you.
     
  11. Corley
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    Corley epoxy coated

    I'd like to understand your 6' headroom requirement in the saloon better. Are you that tall? Or do you just feel claustrophobic in a boat with a lower coachroof. I ask because good headroom in the saloon comes at a price of windage and also generally looks pretty ridiculous in a small boat. Larger boats have more freeboard and can get away with more as far as saloon height without compromising performance.
     
  12. Steve W
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    Steve W Senior Member

    He only wants 6' headroom across the aft end to access the hulls with sitting headroom in the settee area and this is not a big ask, all of the Geminis have this without being overly tall although they could use more bridgedeck clearance but that is largely because they are all overloaded. You do not have to put the mast over the bulkhead, I have an older gemini where the mast was 2' aft of the bulkhead with a compression post going right down through the table to an I beam that spans the hulls. Not saying its a good setup but it did work. Oh, when i say an I beam i mean an actual steel I beam.
     
  13. saltifinch
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    saltifinch Junior Member

    Ok, its just a drawing made on Windows Paint, using a mouse while lying sick on a bed. You're seriously overestimating the accuracy of the dimensions.

    Catsketcher, I appreciate the actual constructive criticism you wrote. But you're reading too much into the drawing. All your theory on boat mechanics don't mean anything when this design is empirically proven to work. Like I said, this is essentially a Tomcat 970S. This boat exists and works quite well. I just simply drew some dimensions not to scale.

    The bulkhead will be forward of the saloon, to which will attach the mast, with the master bunk ahead of that. You're right, it won't go straight to the front of the deck, as there needs to be room to sit up without dropping bridge clearance, thank you for pointing this out.

    I am 6 feet tall, and I want to use this boat as a liveaboard also, at least for some time. A doghouse extending just to the reach of the stairs will allow for comfortable access to the hulls, and shelter for the pilot.

    I'm not obsessed about windage, if I lose some efficiency for a boat that is more comfortable, I am willing to take that.

    I will attempt to redraw this image with your comments in mind.
     
  14. saltifinch
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    saltifinch Junior Member

    Again, thankyou for your criticisms, and hopefully this new drawing solves some of the issues you've mentioned.
     

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  15. bscatam
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    bscatam Junior Member

    Catamaran Design

    To design a cat is a really a very difficult and time consuming process. And it requires a lot of knowledge. I am in the process after 3 years of studing. Work in progress.
     

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