524Re: Easily driven boats (and study plans ordered)
- Jan 17, 2005Leo,
Wow, you certainly have stirred up some good responses on this thread
and the previous! I too am looking for a cruising boat to build; but
my cruising would be on a lake about 100 miles long by 40 miles wide
so the size requirements are different. However, the cost of diesel
fuel here in Nicaragua is high (not as high as Europe) and I am
looking for a very efficient hull in the 23-26 foot range. I would
like to use an agriculture air-cooled engine in the 6.6 to 13 HP range
with belt drive. I can buy a 6.6 for $639 and an 11 HP was quoted at
I really like the idea of a motorsailer for the assist it can give as
well as dampening the motion in these sometimes (well lots of the
time) rough waters. Some of the local transportation pangas use a 9.9
to 15 HP outboard and a sail. So, today the check was put in the mail
for study plans of "Little Water", "Little Silver" and "Lady of the
Lake". Okay, I know a stern-wheeler is not efficient, but "Lady of the
Lake" is for another project!
Mr. Robb White suggested "Little Water" but it is a fishing boat and
the cabin is minimal. Still, it looks attractive even though I don't
need the extreme shoal draft. (One inch draft per foot of deck length
would be fine.) "Little Silver" is a V-bottom motor-sailor with a nice
cabin. I wish I could remember the design where the Atkins compared
the SeaBright Skiff based designs with V-bottom designs. For our lake
conditions, the V-bottom may be the way to go.
Oh, some more design considerations! Exterior plywood is almost
impossible to buy, and forget about marine grade! Good boatbuilding
woods are available but not cheap; and forget about asking for
quarter-sawn! There is a good wood here for steam bending (locals soak
it in water) but I haven't priced it yet. And I won't be building
alone. Our young carpenter working on things for the house is an
artist with wood and his rates are affordable!
I love this group!
p.s. And I haven't entirely excluded Russell R. as a cheap option!
--- In AtkinBoats@yahoogroups.com, "Leo" <leochill@y...> wrote:
> Back when internal combustion engines were first becoming available
> whether gas or diesel these engines were massive chunks of cast
> iron and had very low HP to weight ratios. Maybe on the order of 1HP
> per 100 pounds. Today's engines might have 10-20 HP output per 100
> pounds of weight. Refer back to the comments about Rescue Minor and
> how the bow acts without the motor weight that Atkin specified for an
> So back when Atkin was designing, motors were very underpowered and
> the hull really needed to be "slippery" to fully take advantage of
> the low power that was available in those days from IC engines. And
> yes, I know I'm sorta downplaying, for now, the effect that torque
> has on turning a large propeller slowly.
> Based on my reading, early displacement power boat hulls evolved from
> sailboat hulls that were "sorta" efficient. Obviously the science of
> designing efficient displacement power boat hulls progressed rapidly
> as NA's learned what worked best and what was less desirable.
> It seems to me that as engines become both more powerful and the
> power to weight ratio improved, that the hull shapes started moving
> away from what slipped through the water easiest and began evolving
> into the "fat-ish" hulls of trawlers and cargo boats and that
> evolution has progressed into the modern plastic floating apartments
> that grace (or is that disgrace?) trade magazines and marina's the
> world over.
> Having recently read a history of the Whitehall Rowing boat, I began
> to wonder why this hull form, with its fine entry, generous mid-
> section and wineglass stern wasn't expanded upon for inboard power.
> What's the drawback from scaling this general design up to make it a
> 30-40 footer? Perhaps direct 1:1 scaling isn't practical, but why
> couldn't one incorporate the fine entry, general midships section and
> the fine stern sections into a power boat hull? To my very untrained
> eye, it appears that Atkin did use some of these three design
> principles in several of his designs.
> IIRC, from Gerr's books and others, a large diameter, aggressively
> pitched slow turning propeller is more efficient for moving a
> displacement hull than a smaller less pitched propeller turning at
> higher speeds. Or is my memory getting as gray as my hair?
> It seems to be a difficult task in today's world to find folks that
> agree with this philosophy. Almost all modern (inboard diesel) boat
> propulsion systems rely on high speed engines many with
> turbochargers to turn a smaller wheel. Gear ratio's in the 2:1
> 2.5:1 are common. This translates into prop RPM's from the low range
> of 750 RPM to a high of 1800 RPM when the 2:1 geared engine is wound
> to 3600 RPM.
> Yet just a few decades ago we had engines that idled at 300-400 RPM
> (or less) and had an operating RPM range from 700 to 1200. These
> engines ran for literally tens of thousands of hours nearly trouble
> free. Nowadays we often hear of inboard diesels needing replacement
> in as little as 2000 operating hours. Throwaway power. Yuck!
> I believe that we can generally agree that 1) how/where you want to
> go with a boat, 2) how long you want to stay aboard and 3) how
> much `camping' you're willing to tolerate determines what type, size
> and amenities we'll need. And finally, 4) aesthetics. How a boat
> looks to our eye is vital. And as each of us has different needs and
> tastes, I believe all 4 of these considerations are classic cases
> where Your Mileage May Vary. ;-)
> Addressing #1. My wife is a teacher and a decade younger I want to
> be able to put the boat on a trailer and go for her summer vacation
> to Alaska via the inside passage this summer, The Erie Canal next
> Maine and Nova Scotia another Trent-Severn waterway another. When
> we're both retired then on to the Bahamas for the winter and back to
> Alaska for an extended trip. Maybe put it aboard a freighter and
> ship it to France for a couple of years living on the European canal
> Addressing #2. At first we're only talking about 10-12 weeks at a
> stretch. Later it could be full time for a few years or at least 8-
> 9 months out of 12.
> Addressing #3. At first we can tolerate a bit more `roughing it'
> for a few weeks, but some of the things that we will not do without
> (not an all inclusive list) 1) space to get away from each other when
> need to. 2) a great galley with room enough to prepare a full meal
> without contortions of the body or with the pots and pans. 3) full
> length and width berth(s) with comfy mattresses. 4) a separate full
> sized shower no sopping TP! 5) an all weather pilot station
> either fully enclosed or enclosable with canvas.
> Addressing #4. I just plain like boats that look like a classic
> boat. None of this plastic fantastic modern European shapes for me.
> Give me the lines of an Elco or a Lake Union Dream Boat or a double
> ended Salmon Troller or the shape of a Whitehall. Give me a nice
> sheer and a plumb bow. How about bronze ports either oval or
> round and a rearward sloping windshield instead of that forward
> sloping monstrosity, regardless of how practical it is. Bottom
> line? Spare me the angular constructs that adorn so many marina's
> and boat shows.
> Finally, I think we can all agree that petroleum products oil, gas,
> natural gas and diesel fuel are just going to get more and more
> expensive. The days of a buck a gallon diesel are probably long
> gone. So this means that to have a boat that I can afford to
> operate, it must be very efficient. I'd consider 7-10 statute MPG
> the minimum this should equate to less than 1 gallon per hour of
> running, in other words, 6-8 knots cruising speed at less than 1
> GPH. Better than that is just that, better. I think that this is
> achievable in a 35'-ish boat if we don't load it down with a ton of
> canned goods. Something less than 20,000 pounds 15,0000 better
> yet - fully ready to cruise would be the goal. My preliminary
> investigations and calculations indicate that given the right hull
> design and using modern epoxy/ply building methods this appears to be
> an achievable goal.
> Finally, utilize a big ol' slow turning engine with either a VPP or a
> big-ish wheel and set it up to cruise at a V/L of about 1 to 1.15 at
> the most efficient fuel consumption RPM for the engine probably
> less than 1500 RPM - and one should have a boat that one could afford
> to build and run without breaking the 401k and would be worthy of
> being called a Retirement Cruiser.
> Addressing Manfred's comments about River Belle This would be a
> perfect boat for cruising the ICW and the various canals, waterways
> and rivers. But would this design be suitable for an Alaska trip or
> a trip to the Bahamas or a summer on the Great Lakes or the coast of
> Maine and Nova Scotia and Newfoundland? Perhaps not. So I still
> think to go to all the various places that I'd like to visit before I
> die, I need a boat with some sort of keel and the ability to take
> some rough weather should the unfortunate happen.
> Any other suggestions?
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