turning a sailboat into a motorsailor

Discussion in 'Motorsailers' started by Dave Gudeman, Dec 12, 2009.

  1. Dave Gudeman
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    Dave Gudeman Senior Member

    In case anyone is interested, my boat buying is temporarily on hold until I have done some research on power boats (or until I change my mind again and decide I can live with displacement speeds).

    Trimarans are probably out because they would cost so much to dock, but I am curious about one thing: why are they so slow on engine power? I've seen several listed that claim to do up to 20 knots under sail but none of them go faster than 7 knots under power. Why would they design a boat like that? Why not put in a more powerful engine so it could still make good time when the wind is not favorable?
     
  2. FAST FRED
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    FAST FRED Senior Member

    Why not put in a more powerful engine so it could still make good time when the wind is not favorable?


    Multihulls usually suffer from more surface area underwater (wetted area) than momohulls.

    While the price of going FAST is lower with the less wave making resistance from really skinny hulls , the price of all that wetted surface still has to be paid. When the wind blows 40K its fine to use free energy to go 20K.

    A fast cat or try under power would have close to the fuel burn of a monohull, 1 nm / gal ,the top speed might be 5 or 10% higher.

    For cruising the huge weight of fuel required to "go fast" and the weight of a far larger could handy cap a multihull (Light Light Light!) to the point of unsafe at every speed.

    FF
     
  3. ecflyer
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    ecflyer Junior Member

  4. ecflyer
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    ecflyer Junior Member

    Sorry Dave, I forgot to specify Version C, D or E, on that Roberts 434.

    Earl
     
  5. SeaJay
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    SeaJay Senior Member

    Dave,

    About 8 years ago, I started on a similar quest such as you have described at the beginning of this thread. Our intended use and requirements are remarkably similar. Although I have an engineering background, I soon found that I had a lot of erroneous preconceptions about how boats worked. For the first couple of years I read everything I could on boat design…the recommendation of Gerr’s “Nature of Boats” is spot on. If you really want to knowledgeably evaluate the pros and cons of various designs you need to have at least a solid understanding of that book.

    With a couple of years of study under my belt, I started looking at what was on the market and couldn’t find anything that really fit my bill (or my billfold as the case may be!). However, over the intervening years there have been a lot of pilothouse and deck saloon designs hit the market. And guess why? A lot of boomers like me are getting a little too “mature” for a full day of sitting on the rail while tacking through the Berkeley slot. Sometimes a cocktail in the pilothouse while anchored in Richardson Bay and watching the fog roll in the Gate has a lot of appeal! ;) Anyway, there are a lot of these designs out there but they aren’t usually old enough to have depreciated into the “economy” class. Here is an example of one (Shannon) that influenced my thinking. http://www.shannonyachts.com/sailpilot.html (I’ve got a large collection of links to similar designs if you are interested.)

    Anyway, at heart I’m a builder and a designer, and just wanted to build something rather than buy. Ultimately I came across a 46ft bare hull on e-bay that I thought would be a fine platform for what I envisioned. I wanted a “fast” sailboat hull, lots of reserve hp, pilothouse, simple rig, with comfortable accommodations for two. Make no mistake; this is not an economically sound exercise. I doubt very much that I can build for less than I can purchase…especially when you consider resale value. But hey, it’s my money and my time. If you’d like, PM me and maybe come up to Sacramento and see the project and we can talk “motorsailers-on-the-bay”.

    Best Regards,

    Doug
     
  6. rickinnocal
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    rickinnocal Junior Member

    I just bought the 54' boat shown in my thread "turning a motorboat into a motorsailer", and I'm also in the SF Bay. I found three marinas with slips available before I bought, and settled for staying in Berkeley where it already was. (And I'm not on and end-tie.)

    Richard
     
  7. AlexMorozov
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    AlexMorozov Custom yachts

    -----------

    Hi, working on my new project Soler-34 I found many "wishes" from you post in my list.
    The small (34ft ?) not always means slow. I calculate 12+ knots on version MS (motorsailer) with 115 hp outboard. The small size as 34ft is the minimum length for more or less comfort for living aboard. The length is also dectaded as most marinas here in Europe are optimized for -12m (40ft) boats, which are always available and can be cheap. The 50ft is rather big boat for handling by single, if not stay all year in marina, but for marina living is the best size for sure.
     
  8. FAST FRED
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    FAST FRED Senior Member

    "I calculate 12+ knots on version MS (motorsailer) with 115 hp outboard."

    Do you have a displacement well under 5000lbs?

    FF
     
  9. AlexMorozov
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    AlexMorozov Custom yachts

    The estimated weight about 3500 kilos(about 7000 lbs), but it is only one issue, the second is the hull form and proper trim for motoring at 12 knots in gliding mode. I made 8 knots with 5000 kilos and 40 hp with similar hull form, but with 11 meters WL.
     
  10. viking north
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    viking north VINLAND

    Dave, having converted a big Newfoundland traditional trap skiff and two lifeboats into motorsailers and about to convert a big surfboat/lifeboat into one i can vouch from experience that hull style and displacement plays a big role in the motorsailer class of vessel. Theres nothing like heavy displacement to offset the windage of the higher wheelhouse , and carrying capacity of the bigger engines associated with proper motorsailers.I know there might be some feedback here on my general statement but i do have the experience of hands on (building) and sailing in rough conditions of what i have built. Geo.
     
    Last edited: Jan 10, 2011
  11. Ozimo
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    Ozimo New Member

    This would be the preferable choice - OR you could purchase a boat with one already installed.

    You are much better off hiring a professional in a boat yard, than trying to do this yourself.

    We worked with wood for many years before returning to metal boats. Woodworkers are the most difficult to find and draw the highest pay b/c there are so few of the good ones.

    If you want a motorsailor - buy one, but don't try to modify. Get a boat with enuf hp to do the job properly.
     
  12. Wavewacker
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    Wavewacker Senior Member



    Check out an older Carri-Craft catamaran, a couple show up occasionally and appear to be very good deals for the money for the living space you get. They have been used off shore.
     
  13. viking north
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    viking north VINLAND

    Powerboat/motorsailer

    Dave reading between the lines I think this is what you are searching for. It's from an article/advertisement in the Jan. 1956 Rudder magazine(Boat Show Issue) I'm having problems with my scanner/computer language so I'm not sure if I can post the document here. If not I will e mail directly to you and if you would be so kind you can then post it for forum input. I doubt if you will be able to access the origional drawings/design but it will be a benchmark for one of the professional designers on the forum can check thru their stock designs to present a very similar vessel.--Geo.

    A yacht is not defined by the vessel but by the care and love of her owner--
     

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    Last edited: Aug 18, 2011
  14. brian eiland
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    brian eiland Senior Member

    Rhode's Discoverer

    I think you need to darken up that imagine on your scanner before you post it. The software should allow this minor adjustment.

    Here is my idea of a beautful monohull motorsailer in the theme you present Viking North... the Rhode's Discoverer
    http://www.boatdesign.net/forums/boat-design/motor-sailers-philip-rhodes-john-alden-16721-5.html#post472327

    Now here is a lighter weight concept, Thai picnic/weekender (you could add a small sailing rig to this):
    http://www.boatdesign.net/forums/multihulls/weekender-picnic-powercat-33751.html

    ...or there has to be some older (even wooden) vessel out there that cound be fixed up or converted...depends on your budget?

    http://www.boatdesign.net/forums/motorsailers/monohull-verses-multihull-powersailers-motorsailers-4499-15.html#post476379
     

  15. viking north
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    viking north VINLAND

    Yes the Rhodes is also very close but in a more modern theme. My thoughts on the Rudder article was it looked very close to an old style Novi(modern lobster boat hull with more deadrise) and the modern versions are fairley plentyful in glass either as a bare hull or used.

    A yacht is not defined by the vessel but by the care and love of her owner--
     
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