Maximum simple trailerable power cruiser - looking for ideas

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

  1. tom28571
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    tom28571 Senior Member

    Steve

    I have a friend who built a 39 foot power cruiser that sounds a lot like your wish list although it had a flat bottom. It did weigh the same at 7500#. Big comfortable, solar powered fridge, etc. and legally trailerable. Nice boat, but: It was never trailed but was moved commercially for many dollars. Would I consider this boat or one like it trailerable? I would not, but some have other thoughts. In fact, I have never seen an actual 40 foot cruising powerboat trailed by an individual.

    After a couple cruises up and down the coast, the boat was sold and plans bought for one of my 28 footers. No work has started on it though and I do not know about the future.

    I think 7400# is about right for a flat bottom of these dimensions but think that in order to match the stability, a V bottom would necessarily add a significant amount to that.

    There are a limited number of ways to arrange an interior of a boat, especially one restricted to 8.5 fee of beam. In truth, only one cabin can be claimed to be private and all the others must have pass through capability. If the house is carried to the deck edge, the all must handle the pass through. More food for thought in saying that double the length does not necessarily double the real space.
     
  2. Steve2ManyBoats
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    Steve2ManyBoats Junior Member

    Tom - Great observations - Thanks!

    I understand how the average boater might get in over their head with a 7,500 lb, boat that was 39 ft. long. If a person's experience is pulling daysailers or cuddy cabins, a 39 ft. boat could be clearly overwhelming. If they aren't comfortable driving a one ton diesel pickup pulling a 4 ton load, that could be overwhelming too. I completely agree that if you're not up to the task of trailering a large, heavy load and have to delegate that task to professional movers, you also just included marinas with travel lifts for launching and upped the cost and hassle factor to the point where the boat is too expensive and problematic to use. I agree that the whole point of cruising is to relax and avoid hassles, not incur them.

    However, I'm not the average guy. I'm 53 and am fortunate enough to be retiring in 2 years. I still ride 60 mph jet skis, canoe, sail small overrigged planing skiffs and fish offshore. I'm pretty fit and want to take advantage of that fact. I've also built a bunch of boats, some to my own designs and have a lot of experience in towing pretty big offshore race boats. I'm pretty sure that, if I can get a workable design, I can build it and use it.

    I understand that the design brief I'm advocating is not for the masses. Not everyone is up to trailering a boat that's 40 ft long weighing 4 to 5 tons. I've done it before so I know I can do it.

    When it comes to privacy with a long, skinny boat, you're right on target. It's going to be hard to retain privacy, particularly if interior volume is going to be maximized by no side decks and all forward and aft passages conducted in the cabin. I'm not saying that that's preferable, but it does maximize interior volume. However, in the design brief, I noted that this is a cruiser intended for only a couple. Not worried about overnight guests. If some come aboard, they can rough it in the salon. Actually, the roomerans we're most interested in, if it comes to that, are completely open, like the Tomcat 9.7, which is intended only for a cruising couple.

    I haven't started sketching the interior to confirm that a 40 ft boat is actually needed. Perhaps I should. It may well be that a 36 ft boat might work.

    Regarding your comments about a V bottom boat upping the weight, I really don't think that's so. I've designed and built more than a few deadrise workboats out of ply where I used relatively thin ply in a box grid - stringers and frames - from hull to deck/sole and I am usually able to keep weight below what a flat bottom boat would be, particularly since the hull bottom panels are developed curves (conical, actually) and I can generate a fair amount of stiffness just by loading the panels, whereas a flat bottom boat needs a lot of panel thickness just to maintain stiffness.

    Tom - I know that you have a 28 ft. trailerable cruiser that it seems you thinks is about as big as one should go. If it's not an imposition, could you share what the interior accommodations for your Bluejacket 28 look like? It would give me a better feel for your thinking on this subject. Again, thanks for your contributions to this thread. Most appreciated.

    Steve2ManyBoats.
     
  3. Willallison
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    Willallison Senior Member

    Steve,
    I doubt Tom was referring to the strength of the bottom shape - a v-bottom (especially if there's a bit of convexity in it) is stronger than a flat bottom. But as you increase deadrise, you generally have to increase displacement as well in order for the chines to remain immersed at rest, which is an absolute must if you want the boat to have any sort of initial stability at rest. (There is one way around this, which works quite well on outboard powered boats, which is to have the bottom of the transom open to the rear, allowing water to fill a void under the cockpit floor whilst at rest).

    I've attached a couple of quick sketches (and apologies for the quality, coz they were quick!) of possible layouts. Pay little or no attention to the styling of the profiles, they are just there to give an idea of the relative volumes.
    The top one has side decks, with the main saloon located up. The second has a full-beam saloon located 'down below', like a sailboat. I would want quite large deadlights in the topsides to provide light and a view, with this version.
    Both are outboard powered, though I would probably prefer a sterndive installtion in a boat this size. It allows a larger diameter prop without compromising on the shoal draft... and makes getting hot water a whole lot simpler!
    As I said before, doing this before completing an SOR is jumping the gun somewhat, but hell..... it's the most fun part!:)
     

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  4. tom28571
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    tom28571 Senior Member

    Steve,

    The couple I referred to does not lack any ability to carry out a program similar to yours, they just didn't want to.

    I'm not trying to be argumentative, just add to an interesting discussion. On the weight thing, I am not referring to the weight of the boat. On that point I agree with your statements. What I refer to is that the displacement of a V hull MUST increase over that of a flat bottom hull OF EQUAL WATERPLANE if it is to retain the same stability. This is just one of the things that comes up in the design process.

    A layout of the Bluejacket 28 is at: http://www.bluejacketboats.com/bluejacket_281.htm

    I'm not pushing my boats, just saying that this balance of the various inputs to a good trailerable cruiser is what satisfies me.
     
    Last edited: Oct 21, 2010
  5. Steve2ManyBoats
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    Steve2ManyBoats Junior Member

    Great input

    Tom:

    Understand completely your point regarding the effect of a v bottom on waterplane and submerged volume. I'm sorry I misunderstood your point. I also appreciate the plan view drawing of your Bluejacket 28. It's a very handsome design.

    Will:

    Really interesting take on this idea. It's a little more modern looking than I was thinking of, but I like the lines. I'm going to have to stare at these sketches - particularly the accommodations - for a while. Much appreciated.

    This thread is getting very interesting.

    Thanks...Steve2ManyBoats.
     
  6. Willallison
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    Willallison Senior Member

    No probs Steve... as I said this part of the design is always the most fun... and there isn't really any styling there.. just sketches to compare the various vloumes...
     
  7. brian eiland
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    brian eiland Senior Member

    Canal Boat Theme

    I went back to your original posting to look at a couple of items that caught my attention. I believe your requirement to go to the Bahamas in this vessel greatly influences some decisions on the design. If you eliminate this requirement, and if you respect the idea that you will have time to pick and chose certain trips (such as a couple of questionable crossings in the Intercoastal Waterway, etc), then I think a canal barge type vessel could give you the most bang for the buck.

    I was just looking thru a few of these fancy canal barges,
    http://www.french-at-a-touch.com/Travel/bargecruises2.htm
    ...and detect basically an almost ocean freighter type hull with straight sides and likely square bottoms....relatively easy to build, and lots of volume for the length. How about a steel I-beam keel and paneling via a sandwich of plywood glued to something like Nitacore? Have to think about this some more.

    For trailering I would give a serious look at some sort of torsion bar axle arrangement for either the trailer, or possible incorporated into the hull of the vessel itself. The alum trailers are just too flexy for this application.

    Just some thoughts for the morning
    BTW I may come down to Annapolis this afternoon...up for a coffee or drink?
    Brian brian.eiland@gmail.com

    PS: I'm still thinking about a 50' version of that Roi Soleil with cabin sides out to full beam, but cosmetics to give her the illusion of sheer, etc :cool:
     

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  8. FAST FRED
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    FAST FRED Senior Member

    A 40 ft boat might require the wheels to be 20 ft back , and this is lots longer than many paved ramps , that mostly handle 20-25 max sized boats. IF more weight were placed on the 5th wheel, or ball hitch, the boat would be harder to move in your storage area.

    Rolley Polly in a rough harbor is a concern .
    My solution would be a easily rigged ( across the bast) aluminum pole of about 15 ft.

    The dink would be fastened to the end of the pile and slid away from the boat.

    Instant catamaran, in terms of action from waves on the beam.

    Solar patio lights are cheap, and with better ni cads will last all night to warn close traveling folks.

    Good chain, no outboard would remove much of the dink theft problem.

    Although the aluminum pole hooked to a 12v, 20 mile cattle fence charger would be even more secure.

    FF
     
  9. brian eiland
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    brian eiland Senior Member

    Attached Files:

  10. brian eiland
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    brian eiland Senior Member

    Fold Outs (reasonable)

    This is a little more reasonable...:idea:
     

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  11. Steve2ManyBoats
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    Steve2ManyBoats Junior Member

    The canal boat interiors are nice and seem to maximize beam, but...

    Brian:

    I really hope to be able to keep the max speed at about 18 mph. That means the boat will have to plane to reach this speed. It might be able reach the high intended cruise speed - 12 kts - in semi-displacement mode. I also really would like to be able to have sufficient wave penetration to make short ocean hops - like the open sections of the ICW and the trop across teh stream to the Bahamas. Attractive as the interiors of teh european canal boats are, I really don't think that design is going to work for what I have in mind.

    I also don't see the need for a steel beam. Multiple ply stringers that run from deck/sole to hull ought to provide sufficient longitudinal stiffness. Steel also isn't going to do much to minimize weight.

    I like the idea Will sketched. I might opt for a larger cockpit with an open hardtop that can be enclosed with sunbrella/eisenglas to make a second salon or an open air lounge.

    I'm searching Mariner's Museum for ideas for the aesthetics - sheer line, hull lines, house lines. I think this might be a workable concept.

    I was talking at a local marina last weekend with a guy who trailers a 32 ft Regulator with a pair of V8 Yamahas - your basic full-tilt, maxi offshore center console sport fisher. His boat lives on his trailer and is significantly heavier that the boat I envision. He has a big pickup to drag it around and seemed to know what he was about. Claimed that he fishes (trailers) a 500 mile radius, depending on seasons, and had little problem finding ramps and getting in and out of the water. I told him about what I was thinking about and he thought the plan was workable. I still do, too.

    I'll be in Annapolis all next week and next weekend if you want to get together and talk about making my Firefly fold.

    Thanks to all...Steve2ManyBoats.
     
  12. brian eiland
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    brian eiland Senior Member

    Last edited: Nov 21, 2010
    1 person likes this.
  13. Steve2ManyBoats
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    Steve2ManyBoats Junior Member

    Very interesting...

    Gives me some good ideas. It's interesting that most of the designs use a fairly open space floorplan. Sure seems to me that a design that's nearly flat with little to no deadrise aft with some vee to the forward sections ought to work.

    I'll PM you to talk about making my Firefly fold.

    Thanks...Steve.
     
  14. brian eiland
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    brian eiland Senior Member

    Rolling Barges

    Hey Steve,

    Have a look here:
    http://rollingbarge.com/

    http://rollingbarge.com/party-barge.htm

    •Giant DoubleDeck Pontoon Boat / Party Barge.
    •17 feet wide and 19 to 29 feet long on the water.
    •8 1/2 feet wide on the highway
    •Tow with any full-size pickup or SUV
    •Fold out in 20 minutes
    •Up to 500 sq ft Main Deck, 150 sq ft Upstairs
    •DOUBLE the size of the largest pontoon boats!

    ...just some thoughts :idea:
     

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  15. u4ea32
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    u4ea32 Senior Member

    Just got back from a month in the Caribbean: Stuart FL to Antigua via Bahamas, VI, etc.

    Too much stability is a bad thing: leads to rapid rolling. Any rapid motion leads to injury and discomfort.

    Pangas: these are common and very sea worthy. Long, skinny, sharp entries. Some without chines, some with chines starting midship and very flat deadrise aft. No apparent difference in effectiveness (remember, the transoms are narrower than max beam on these boats).

    But a fine entry with a wide transom leads to an unbalanced, uncomfortable, wet motion: the bow plunges and the boat stops (and the people get hurt).

    Open plan interior: its really the way to go. There is no privacy on boats! OK, enclosed head ;-)

    Be sure to have dorade vents, and not just hatches and windows: you really, really need ventilation below when its too wet to open windows and hatches.

    The feeling of spaciousness is maximized by having big windows, with the bottom of the windows no higher than, say, 3 feet: so windows come down to counter tops and to tops of settees. Being able to see out to the horizon sure makes it seem spacious! You don't notice how cramped it may be at your feet.

    Outdoor shaded space is very important.

    Convenient dinghy storage is essential.

    If you actually intend to cover miles at sea: Use the bow for storage. Don't put the head up there, don't put a bunk up there.

    Outboards are better: diesel smells, is noisy, and way more complicated when all the systems are included. Outboards are worldwide, so fuel and maintenance is easy.

    7 knots is plenty for speed when going offshore. Even with 60 feet of waterline, slowing down a bit improves seakeeping dramatically (and reduces all the irritations of noise, vibration, fuel burn, ...). Too slow if you need to get back to work on Monday, but its really fine if you have unlimited time (this is a boat for retirement, right?)

    Stabilizers are not nice when the going gets rough. Great when you really don't need them, dangerous when you do.

    Its much, much more "comfortable" when you can PREDICT the motion of the boat in pitch, roll, and heave. The amount of motion isn't as important as the predictability of motion.
     
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