Sailboat as a powered cruiser?

Discussion in 'Motorsailers' started by Bill Fish 6, Nov 15, 2004.

  1. Bill Fish 6
    Joined: Nov 2004
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    Bill Fish 6 New Member

    Hi all....

    This past summer I got to use a friends inflatable avon with a 4 hp motor....and I really had a blast spending all day cruising around at about 4 knots in relative peace and quite and only using a few gallons of gas doing it...of course that thing was about as hydrodynamic as cinder block....

    It sure was the opposite of when I was a kid when and my Dad would take us on a planing powered fishing boat, where we got beat to hell, went nearly deaf, got soaked always, and burned gas/money like the Rockefellers.....

    So, from my recent "cruising" experience, I've realized that slow and easy could be pretty darn fun....and I could actually stand going so I could cruise just for the sake of cruising on a nice day....or if I wanted to dive or fish I could stand taking ALL day doing it (because of the slow speed)...might as well since after a half day of fishing or diving Im so wiped out anyway I spend the rest of day just vegging might as well vegg out putting back to port in the boat....

    Now, lets say I get the typical mostly enclosed small sailboat. Say 18 to 22 footer.

    How many HP would I need to push such a vessel at hull speed? And say for example that it calculates at 4HP, how much more power should I have in reserve to fight wind, waves, bad weather, avoiding running the engine at max power etc etc....

    As an aside, around here...gulf of mexico, Pensacola Florida area...the ocean weather is not often bad....when its bad for long periods of time you know its coming and can avoid it....and generally if its something unexpected (ie pop up thunderstorms) it only last a few hours at its not like I'd want a boat able to fight a New England type noreaster for days on end....and my uses would most often be the bays, intercoastal water way, and the occasional ocean jog 10 to 20 miles east/west of "the pass" and about 10 miles offshore max...

    Would a sailboat (without any of the sailing thingamabobs on it) make a decent day/long weekend powered cruiser when used in nice weather? And would it be reasonably safe (if not comfortable) in bad weather (compared to a high powered "normal" powerboat)?....

    And would a sailboat in reasonably decent weather, say moderate swells, waves or chop, be a fairly comfortable boat when at anchor? (I would think the keel and its moment of inertia would help there)

    And I certainly like the idea of economical boating being of a rather cheap nature myself (and being poor at the moment makes for a really bad combination :)....

    Give the hurricane Ivan damage here, I could probably get a small sailboat hull here for nearly nothing (hell, some are still in the trees in the woods!).....amazing what a 40 foot storm surge will do!.....and a small outboard is no big deal....but I imagine trying to rigg out a sailboat with all the sailing "stuff" would probably make me faint cost wise.....

    take care and dont get to upset with my blasphemous quest!

    Any comments on the pros, cons, or possible gotcha's greatly appreciated!

    take care

  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Sailboats have less initial stability then power craft. This means they are designed to roll from side to side easily for several degrees (the amount of roll is design dependant) and this will make a cruiser that moves quite a bit while anchored or drifting. When the sails take a set, the boat flops over on her bilge, then firms up. A centerboard boat will have a higher range of initial stability then a deep fin boat, but both configurations will roll much more then a typical powerboat.
    A power boat has a high rate of initial stability and will remain reasonably flat under power and at anchor or adrift.

    The usually arrangement for trailer born sailboats is centerboard or daggerboard. Fin keel boats are usually intended for around the buoys work in the size range you're looking at. The board boats will have a trunk intruding into the cabin space, making the interior divided up some what, an inconvenience powerboats don't have.

    The sailboat will make a good low speed craft, where economy is concerned. The hull shapes used are much kinder to passing through water then the average powerboat, which is designed to blast across the surface. Power boats will provide more room for the buck as far as accommodations go. You'll be able to provide standing headroom and seating arrangements for several, but it will cost power to push this.

    Used sailboats, aren't that expensive. Used sails can be had reasonably also. You can even make sails out of tarps and carpet tape. Yes, if you replaced all that needed replacing on the rig, she'd eat you out of house and wife, but most times you can get by with just needed repairs and budget the wish list for other times.

    I saw a 22' 1972 O'Day for $1,200 including trailer and "hardly used" sails in the paper the other Sunday. You'll likely have to rewire the trailer, new tires, maybe a hitch. The boat will require lots of cleaning, caulking and going over, but if kept out of heavy air and storms may need very little else. Sailboats use surprising little fuel, especially with the sails up. If using power (in fact, motor sailing), you'll want some of the sails up to steady her down on one side, or she'll roll back and forth and be uncomfortable.
  3. Olle

    Olle Guest

  4. tspeer
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    tspeer Senior Member

    Seattle Naval Architect Paul Bieker has an Ultimate 30 sailboat hull that he converted into a powerboat. It makes for quite a striking runabout with its plum stem, fine entry, and rakish cuddy cabin. He says it's the way of the future - easily driven but still capable of decent speed.
  5. tschienque
    Joined: Feb 2004
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    tschienque Junior Member

    There was an old adage back when engines on boats were true auxilliaries, that you needed 1hp per ton to achieve hull speeed (square root of waterline length) in flat water.
    You won't get scintillating performance and will take time to get upto speed but sounds OK for your situation/requirements.

    I looked at a Santana 20 for some basic figures. LWL displacement etc

    The Santana has 16' of waterline length (easy square root - how nice) would have a square root of 4 so speed = 4 knots. (most sailboats can achieve 1.34 x sqrt of LWL)

    The displacement is 1,360lbs or .6 of a ton

    So theory tells us that a 1hp engine would be sufficient to push boat at hull speed with more than 50% in reserve (only .6 hp required to get upto hull speed).

    Don't know of any 1hp motors, but plenty of 2s, 2.5 and 3s that'll give you plenty of poke.

    Well that's the theory. However, small outboards have small props and are not at their best pushing displacement craft.

    Designers, what (if anything) is wrong with this scenario.

    In tune with your MO consider a 4 stroke, they're very quiet (+fuel efficient).
    Even quieter are electric trolling motors used one on my Dhyer dink for 5 years, gives you a new feeling pottering around anchorages.
  6. Skippy
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    Skippy Senior Member

    If you can find a flat-bottom boat, that should work well. Especially a sharpie.
  7. Wynand N
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    Wynand N Retired Steelboatbuilder

    Hi tschienque.

    Maybe this will give you an idea of horsepower requirement on a displacement sailing hull from a yacht designers point of view. (copied from "Ted Brewer Explains Sailboat Design)

    Attached Files:

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    FAST FRED Senior Member

    "However, small outboards have small props and are not at their best pushing displacement craft."

    The remarkable hunk of British Ironmongery the SeaGull has aux reduction ANd a large sized propellor suitable for really pushing a small sail boat.

    If only they ran ,

    Last edited: Jan 1, 2005
  9. tschienque
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    tschienque Junior Member

    The reason Seagulls were so easy for owners to work on, was that they needed to be.
    Some owners "boasted" of being able to strip and rebuild a Seagull blinforded and in the pouring rain.
    They needed to - considering our weather and how often they broke down ;)
  10. mackid068
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    mackid068 Semi-Newbie Posts Often

    For an 18-22 footer, a 2.5-5 hp motor seems MORE THAN sufficient. To answer your second question, I bet a macgregor 26 (any model) would make a great weekender w/o sails. If it had a 50 hp motor, the manufacturer says, than the Mac 26 can reach 20 (+/- a few) mp/h.
  11. mattotoole
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    mattotoole Senior Member

    I didn't believe it until I saw one doing it! Yes, they can abolutely scream along like a powerboat.

    When not misbehaving like this, small sailboats are indeed very easily driven, and very cheap to buy. I've seen Cal 25s on eBay for like a thousand bucks, nice ones for three. Florida is still full of storm writeoffs that still probably float OK. A lot of small trailer sailors are probably better powerboats than sailboats anyway. ;-) Why pay extra for a boat with a mast, if you're not going to need it?
  12. Schnick
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    Schnick Junior Member

    The mac 26 runs counter to the point here. It has a hull shape similar to any small planing powerboat, making it much less efficient for typical displacement-speed cruising than a real sailboat.

    When you drop the rig on a sailboat, the motion can become somewhat violent, unless you can reduce the ballast or perhaps pull the centerboard part way up.
  13. BrCarr
    Joined: Apr 2005
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    BrCarr New Member

    Yes, and I've Built one, a MotorSailer 21ft.

    Like others, I think this is the ideal boat. Take a look at mine and let me know what you think. Visit
  14. lockhughes
    Joined: Jun 2002
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    Location: Wards Island Toronto north shore, Lake Ontario

    lockhughes ElectricGuy

    Ya. I second the thought about any sailboat design without it's rig (weight) aloft... The motion may not be so great.

    If you want to putter around in silence, and efficiently, look for a hull like this:
    This skipper probably has fuel costs of about 2 cents a mile. Top speed of only 10kts and limited range, but slow things down and you get maybe 20+miles of range, in silence (yah, it's electric.)

    So much easier to sneak up on the wildlife!

    So yah, a sharpie sorta thing. In the pic above, I'd just add canvas for accomodation.



  15. Ssor
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    Ssor Senior Member

    Go to a marina on a windy day and watch the boats and how they respond to the waves. In the marina where I keep Bietzpadlin the center boarders sometimes touch their masts from rolling hard. Some of the power boats aren't much better. Probably you will get more motion from powerboat wakes than from the wind. Cranking the center board down reduces the motion on a small boat but all boats will roll to the waves. As for finding a low priced boat go to the marinas and talk to the staff they know which boats are abandoned by their owners.
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