Stevenson motor cruiser modifications

Discussion in 'Boat Design' started by Gauf, Oct 9, 2013.

  1. Gauf
    Joined: Oct 2013
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    Gauf Junior Member

    So, being a pretty good woodworker who bought plans to build a daysailor 10 years ago (http://www.stevproj.com/IntroPCPg1.html) and finally getting around to building this now that the kids are moved out.

    Anyway, I want to build this as a motor cruiser and modify it to primarily river running. It is a 14' flatbottom hull. I plan on losing the keel so I can beach it and also raise the cabin quite a bit.

    I live on Lake Erie and hope to do some occasional fishing on the Lake as well. It can get choppy out there so I may modify the hull as well. Would like opinions on the following:

    1) Would a shallow vee be a better choice than the flatbottom? Or, perhaps a combo hull. I believe I can make the necessary changes to the plans.

    2) The plans call for 1/2" acx ply glass covered, but thinking of using 3/8" mdo ply and adding a stringer or two for structural support. MDO could save me from glassing the hull, (except the seams). Going thinner ply on the MDO cause it is heavier than the acx and need to trailer the boat.

    3) Any thoughts on an outboard size to drive it.

    Open to any tips and very grateful for the feedback.
     
  2. Gauf
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    Gauf Junior Member

    bcx alternative

    acx not available in my area which is strange but menards has mdo and bcx. Is bcx a possible alternative?
     
  3. michael pierzga
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    michael pierzga Senior Member

    I dont like the materials list for the boat.


    Marine plywood produces a better boat.

    Epoxy resin produces a better boat


    Stainless, bronze or no fastenings produces a better boat.

    You should investigate suppliers in your region.

    World panel has good prices on marine ply. Shipping can be an issue. http://www.worldpanel.com/
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum Gauf. There's a site dedicated to Stevenson designs and another that has many Stevenson designs featured. You should look these up (> messing-about.com/forums and byyb.org/forum <), for build tips and tricks and answers to common issues with this particular build.

    The Stevenson PC wouldn't make the best motorboat, though if you keep the topside structures fairly low sided, it's possible, for use in protected waters. For the great lakes, it's not well suited, as you can get into sea state conditions that will easily overwhelm the boat, as a sailor or powerboat conversion.

    Making a PC into a V bottom will require a complete redesign of the boat's volume distribution, which isn't an easy task for a novice. I'd agree with you in that a V bottom would be a better way to go, for your intended use, but a flat to V bottom conversion isn't as easy as you might think.

    You'd be much better off, if you selected a base design more suited to your desires, then modifying a puddle sailor into a motorboat. You should consider a powerboat plan, such as the FS-14 or OB-15 from Bateau.com, the JackKnife or Nimrod from Glen-L.com or one of the many (100's) other 14' - 16' powerboat designs that are available. These have enough volume to support the additional weight and windage from your proposed modifications and a V bottom to handle the chop you'll encounter in Lake Erie.
     
  5. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    This may be hard to understand but ditching the plans you have and buying new ones that fit your needs will save money, time and yield a much better boat.
    I have been down the road of inappropriate plans, learn from my mistake.
     
  6. Gauf
    Joined: Oct 2013
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    Gauf Junior Member

    Well, I was drawn to this initially as it looked easy and inexpensive to build. No stitch n glue which I hoped to avoid on a "first" build. I do prefer a flatbottom, even if it means staying off the big water. I like leisurely cruises up rivers and overnighting in the cabin. A stable, trailerable boat, with a higher cabin and beachable is what I am thinking. If this plan will accomodate a higher cabin, and lower keel board, then I'd be pleased.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Less then 7 MPH is what you will get with a PC, as a powerboat. If you install a 25 HP outboard you can push this to about 9 MPH, but the bow will be cocked up at an unbearable angle. In a powerboat conversion, you don't need the odd shaped keel used. just a simple 1x4 on the flat will do, saving about 12" of draft.
     
  8. Gauf
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    Gauf Junior Member

    Thanks for the input. Found an old drsign called the Barnaby. A 15' power cruiser that looks like a better fit for me. Seems like alot more work too.
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Barnaby is a classic example of the a plywood over frames build method, adopted in the late 40's and 50's. Barnaby was designed in the 50's and her styling shows this, though could be modernized to some degree. Also, the hull form is a warped bottom, showing it's pre '63 series roots. These boats will do fine, if not over powered or asked to run at too high of speeds or in too heavy of a chop. She can handle chop, but the ride becomes increasingly more uncomfortable with the roughness of it. Slowing down helps considerably in this regard.

    It can built completely epoxy free, though there's a lot parts to make, with frames, gussets, stringers, structural floors, transom frame, keel, etc. This is typical of a plank on frame build and one reason taped seam (stitch and glue) methods are more popular now. With a taped seam build you don't need to make the frames, stringers, etc., often just the hull panels and furniture are all there is to the structure. This savings is translated into materials you must buy, cut and install. Of course, it also means you have a heavy "goo factor" to contend with.

    The plans for Barnaby are quite dated and some materials spec'd will be imposable to get, but substitutes can be made. I wouldn't recommend this as a good first build, mostly because of the complexity of the project, but also because the plans will assume you have some understanding of common building methods and lastly, because there's no living designer to call up or email if you have a question.

    The price is cheap enough, but there's more to plans then the price. A living designer is a handy thing. It's nice to have someone to ***** at or to ask a question of. In this same vain, you can bounce modifications off them to see if you're screwing up something important. Also, modern designs tend to come with more information, if geared toward the home builder. Lastly, modern plans will use modern materials and techniques.

    Barnaby is a full plane mode powerboat, meaning she'll get up and scoot. It also means she'll need a hunk of outboard to do this and slow speed operation will be twitchy. This is a huge difference between a Stevenson PC, which needs only a 5 HP engine and a Barnaby, which will likely need a 40 HP outboard.
     
  10. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    Ask yourself why experienced boater-builders tend to shy away from Stevenson boats.
    Whom, you ask, do they attract? Inexperienced newbies, that's who.
    Again, take this opportunity to learn from my mistake. Don't consider the money paid for the Stevenson plans a total loss. Consider it tuition to an apprenticeship ordinary mortals will never travel.
    Good luck.
     
  11. Gauf
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    Gauf Junior Member

    Thanks, I will explore some more modern designs. I have more time than money right now (like most of America) so perhaps I will try my hand at stitch n glue. Phew, never thought I'd be going this route, but how hard can it be?
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The search for a well suited design can take as long as the build, depending on how specific your needs and desires might be. I know folks that have taken years to make a firm choice, in just a stock runabout plan. Don't be discouraged, there are lots of choices (thousands) in this size range.

    The best thing you can do is make a list, of the things you absolutely just have to have, in the design. Target speed, HP range, fuel efficiency, number of guests and crew, accommodations, build type, material types, propulsion type, general style, maybe some ideas toward hull form, general use you'd expect from her, the usual sea state conditions she'd be expected to tolerate, etc., etc., etc. With this in hand, you can refine you selection process pretty quickly, eventually coming down to a dozen or so, at which point we might be able to help you whittle it down some more. In fact, if you post here what your requirements are, there may be some obvious ones, you haven't seen yet.
     

  13. Gauf
    Joined: Oct 2013
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    Gauf Junior Member

    My requirements? Well, first off it can be no longer than 16' as my garage will not accomodate anything larger. My wife needs good stability and comfort which is why a larger beam, flatbottom seemed logical, however I did hope to get around 15-20 mpg on inland lakes and rivers to kick up a little spray in the face, but this is not a deal breaker. I also hoped to be able to beach her and camp from time to time. A higher cabin would be nice too, but suppose I could figure out a way to raise the ceiling with aid of canvas sides to increase room when we are overnighting. Seems comfort and stability is what I am after here, plus light enough to trailer easily. Now that I think of it, the Barnaby is not right. The BoJEST looks closer to what I am thinking, looks good to me but still a bit large and sits a bit low.
     
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