Maximum simple trailerable power cruiser - looking for ideas

Discussion in 'Boat Design' started by Steve2ManyBoats, Sep 15, 2010.

  1. RichardR
    Joined: Oct 2005
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    Location: Maine

    RichardR Junior Member

    Ultra light motor yacht

    I am developing a motor yacht based on our successful Presto 30 designed by Rodger Martin. It is trailerable with a weight of 5500 lbs. and an 8'-6" beam and can be towed with an F-150. Queen vberth plus two settees, private head, galley, 10 ft. cockpit etc. Drinks 8, feeds 6, sleeps 4 and cruises 2. Nanni 14 hp. diesel or Yahama 9.9 high thrust outboard for a 7 kt. cruise @ 1/2 gph. Centerboard for roll control with 5'-6" draft with board down and 22" with board up. Profile pictures and others in the member gallery.

  2. Jakson
    Joined: Mar 2012
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    Jakson Junior Member

    Thank you for announcing your design here (RichardR). Have you considered a hybrid version?
  3. RichardR
    Joined: Oct 2005
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    Location: Maine

    RichardR Junior Member

    hybrid presto


    I did build a sail version with twin 4kw retractable pod drives. However it had to have a 6 kw dc generator in order to have unlimited range. The boat needs 4-5 kw to power at a reasonable (5 kts.+) speed so a generator is required to have a practical range. I'd be glad to install a system but it does add a considerable amount to the costs.

  4. Jakson
    Joined: Mar 2012
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    Jakson Junior Member

    These updates to the earlier thread posed by Steve2many boats show a couple of designs relevant to the original question/proposal. It shows that even a trailerable motorsailer is possible! I think I've found out enough for my design, but like Steve2manyboats have other designs/ideas to keep me busy. Hope the thread stays open........
    Last edited: Mar 25, 2012
  5. RichardR
    Joined: Oct 2005
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    Location: Maine

    RichardR Junior Member


    The forward mast socket will be retained to allow the easy addition of a sail. Here is a Billy Black photo of Thorfinn sailing in Newport.

    Attached Files:

  6. Captain Sunset
    Joined: Jun 2012
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    Location: Belgium

    Captain Sunset Junior Member

    I am starting construction on my own trailerable boat

    hi, it was very nice to read this thread.
    I am going to start construction (I started getting the materials already) soon on my own boat.
    One of the requirements is also that is will be not to hard to tow.
    It seems that in Belgium (probably the whole of the EU) length is not so much an issue but we can not go above 2,55 meters.

    Further more my design will be built around the attempt to make it solely on electrical power, derived mostly and if possible solely from solar energy through PV panels.

    I will boat only through the canals. For the testing of this first homebrewn ship I will go from Belgium to the Mediterranean solely via canals, most of which are really calm and used mostly by other tourists.

    The maximum speed allowed is 9 km/h mostly, so it is important to get to that speed without to much hassle.

    I plan on boating 2 hours, 3 hours tops a day and use the rest for soaking up sun in the batteries and hiking.

    I use a lot for guestimating what is possible on low kW.

    I am very limited in my budget, but I want to try it with the extra cost just to see if it is possible.
    I looked for example at
    so I know I am cheaper of with a ready to use canal boat with shower and all creature comforts and everything. But I enjoy the thought of trying to be autonomous also very much, like Twomanyboats.

    So for the moment I am looking at making a catamaran like pontoon.
    Each hull would be about 12 meters at the waterline en en the noses will be very pointy (for the hull i am looking to get my hands on second hand GRP piping from construction sites, cheapest I found at the moment is 45 euro a meter and way too heavy made in 3 cm thick walls) These pipes come in maximum lengths of 12 meter from the factory, that is how i came to the 12 meters waterline. The noses and tails will be cut of from old waterpedaloo floats. GRP pipes come in various sorts, but they are really good i think for making my floats because the glasfiber is one long fiber radially crosswired all over the length by robots (like the mesh in car tires). Anyhow, so much to say about the floats alone, but I will continue.

    For the the structural rigidity I use an expensive system. Truss (I use the mark prolyte, the X30d type) This is just Lego for adults. I can lower, widen, elongate as much as i want.

    (the diameter of the floats is 60 cm) so my total volume of the floats is over 6m³

    when I use the psychosnail calculator for 12 m semidisplacement hull (with good entry) for variables 9 km/h at 2000 kg it says I will need about 1,89 kW (like the oldschool longnarrow high speed boats higher up in the thread)
    I took 2000 kg to be the maximum (including myself and 3 passengers) so I am never deeper then 20 cm in the water
    (on a sidenote according to the same boat speed calculator I 'd use less then 1 kw for going 7 km/h (just a fraction under the legal limit)

    About each of these elements I would be happy to elaborate fo course as this is my baby I am making.

    Now for my current question...
    I would like to know if it is possible to just do this with one Torqeedo 4.0 as I would then buy the next one next year for a more demanding trip.
    At they claim to have 2240 watt at the propeller. (for 4000W input)
    My concern is that with such a long boat without much depth it will be hard to steer, even on the a calm trip, because I will encounter a lot of locks for example.
    Perhaps this little thingy is enough to help me out in the locks (i liked it because it has remote control and can be taken out of the water with a foot control)

    I am hoping I don 't have to buy 2x the 2.0 torqueedo now, because next year if i want to go along the Danube they will not be enough. that is why i prefer to try this year with just one 4.0 then save and buy the next 4.0 torqeedo next year, together with the extra battery bank and extra solar array (I plan on installing between 10 and 20 m² PV depending on the budget, if I can 't buy enough PV panels this year, I will use marina sockets more often and buy the rest next year.

    I hope this is the right place to post this entry. (or perhaps i should post this under another thread?) I am happy to fill in on any other details (everything else just gets further and further from mainstream how it is done because of my own strange wishes or strange government rules)

    Feel free to ask me any figures I forgot to mention. (or pictures or links)

    Thank you for taking the time to read through this long post.
    greets, captain sunset
  7. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    part of my modular trailerable cat was fatter 8' wide hulls.

    I was planning on containerable, so I guess that would be 7' 6" beam to be workable, and a OAL of about 38' to fit easy into 40' container with room for outboard or stern-drive to kick up. 8' or 10' tall box, depending.

    I guess with right ballasting and calm water it would be OK as mono hull, and also OK to float while bolting together as a cat....since at 8' will it would need to be two trips to the water.

    Thats a little smaller than OP design specs but would be about the max for 'no complications' trailing anywhere with F-350.

    Frosty, I saw an F-350 pulling a 40' container on a 3 axle trailer the other day down the freeway. But if truck rated at 10K lbs towing and box is 5K lbs and trailer is another 2K lbs that doesn't leave too much useful payload in the trailer.

    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "2. Nanni 14 hp. diesel or Yahama 9.9 high thrust outboard for a 7 kt. cruise @ 1/2 gph."

    1/2 gph on an outboard is perhaps 5 HP.

    A 7K cruise on 5hp would be a real achievement .

    One reason for looking at the Atkin boats with a box keel and reverse deadrise is the ease of loading into a container.

    Wooden 3 inch rollers should do the job , assuming a electric winch could be temporarily bolted into the container , it could be a pretty easy one man job.

    Any other bottom shape might require a rolling cradle (more to store) . UGH!!!

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