Coastal Cruiser

[harry tams]

Originally Posted by u4ea32

I've had an awful lot of fun on boats without standing headroom throughout. For example, standing up in a hatch works wonders.

A couple of weeks ago my wife and I were camping in Big Sur. A couple showed up with a very interesting camper: http://www.tinycamper.com/ It had no standing headroom, but it sure did work. The concept was: stand up when you are outside, and you are always right next to outside. The galley had a hatch that is opened, and then provides cover I guess, shade, and canvas sides can be added for windy days to keep the stove operable. It sure made a lot of sense! They had a lot of fun with that camper.

So imagine a boat that has no standing headroom anywhere, but has a hatch in the head: open the hatch to stand up, erect a tiny tent using the hatch to take a shower. No need for headroom over the berth, settee, dining table, helm seats, just arrange things so these are all next to the cockpit, so you can stand up as you walk to any of these things. Put the galley in the cockpit, with a bimini for times you are boating when you probably really should have stayed home.


And perhaps it could be pushed around with a 4hp outboard: 0.4 gallons per hour flat out. OK, maybe 10HP, so the alternator is big enough to charge the house battery, still only one gallon per hour at full throttle.

Probably could be arbitrarily cheap too.

That is a very beautiful little camper. I like the galley using the wonderful out doors. It would work for some but it would not be for me. It's just too small.

Your idea regarding hatches for additional headroom has a lot of merit. The pop-up roofs on many recreational camping vehicles demonstrates the desirability of low profile to reduce windage and conserve fuel.

A well sealed pop-up could also provide stiffness to large panel that creates the deck thereby eliminating some of the framing requirements or thickness of materials used... it might not even add to the weight.

To keep the cost way down (4HP is about 20kg and $1500), it sure would be nice to be able to use a small out board. Could a more effective prop be created to enable this option?

Harry Tams

[harry tams]

[quote=Rick Willoughby;348685]Harry
I agree that it can be built in glass and not affect performance too much.

I played a little with some arimid honeycomb and had great problems getting it sealed everywhere in a flat panel type construction. I did not use pre-impregnated cloth so that would have helped. Irrespective I believe the integrity is stuffed once the outer layer is breached. Water will get into the voids and "pump" the bond from inside. It will be somewhat like osmosis. I would suggest foam below the waterline but there is not much of that in area - maybe addition tough fabric in the layup.
Rick (Quote)
Rick
Its my understanding that you would not be working with open ended honeycombs. Rather, 200GSM polypropylene film is thermo bonded to each side of whatever core thickness you want. 45 GSM polyester is then thermally bonded to that film to give the superior bond required for the cloth/resin one chooses for the skin. Does this reduce your concern of breacing the outer skin?

To get more serious you need to make a wish list of your requirements. Things like self-righting is important to me. I was relying on battery weight to guarantee this.

Is there another way to get that weight down there? Could the crew be part of the weight required if placed at strategic points (on reflection...they might be unconscious). Fresh water tank with compulsory grey/black water tanks (environmental laws are changing)? Stores(anchor/tackle)?

I never got into an internal layout. It sort of lends itself to neat bunks but making room for stand-up shower in the cabin becomes more difficult.

I'd like to play with that.

A typical 4HP outboard does not have suitable prop to give a boat with this windage serious weather capability. OK for getting about on a good day but not in bad weather. When I get an electric boat going it will have a prop around 600mm in diameter not 200 to 250mm.
Rick (
I'm thinking of significant reduction in cost. Without the diesel (Heavy, stinky, noisy, and pricey). I'd like to begin with the hull/deck/cabin, be able to use a four Hp in a well to be able to use and test the boat , and then add solar/wind/and batteries. I imagine I'd want some of the batteries almost immediately (theres some of the ballast) so that the cabin would have the comforts required (Lights, fridge). Then when it's got the solar/wind power source the 4HP would add to the ballast and be available for emergency power. The 4 HP would also charge the batteries. Can the 4HP be adapted to take a more efficient prop?

[harry tams]

Apologies. I messed up Rick's quote in the previous post. Tried to respond to each section in turn. The result? Rick has been misquoted. Sorry
Harry tams

[FAST FRED]

Can the 4HP be adapted to take a more efficient prop?

Find an old SEAGULL many small units were made for pushing sailboats not tenders and swung large props thru deep gearing.

They are insanely simple motors , so a modern Honda 4 stroke lawn mower power head might be adapted .

FF

[Guest625101138]

Originally Posted by FAST FRED

..
Find an old SEAGULL many small units were made for pushing sailboats not tenders and swung large props thru deep gearing.

They are insanely simple motors , so a modern Honda 4 stroke lawn mower power head might be adapted .

FF

Fred
The biggest prop they will take is about 9". This is on the small side for getting decent thrust from a 4HP motor.

Rick

[FAST FRED]

From the wicopedia,

One main feature of a British Seagull is the gearbox and propellor combination. At first glance, they seem very primitive but due to the high gearbox reduction ratio they are capable of propelling much larger boats than might be expected. The silver Century Plus model, for example, is designed to propel a displacement hull of up to 26 feet in length.

Couldn't find the prop size , but at least they were 5 bladed.


FF

[Guest625101138]

Fred
It seems they can take up to 10". Must be for the 6HP model.
http://www.britishseagullparts.com/e...propellers.htm

I have been working on 500 to 600mm to get decent thrust from low horsepower.

The Mars electric motor I have can be run up to 9kW. With a 550mm prop it could produce thrust around 1400N. At 4kW it can get 800N.

By comparison a 4HP outboard with a 10" (250mm) prop could get about 400N with a nicely made 4-bladed prop. Going up to 550mm 2-bladed gets 620N.

For a boat of this size and shape 400N would be needed to hold in a 50kt wind. You would not choose to be in these conditions but it is not uncommon to be caught out even in sheltered watered.

Wind strength over 70kts is much less common. The windage in this condition is around 800N.

One of the things I did not like about the yellow boat is the windage from the side. I have not worked out what strength would roll it but it would be something that needed evaluation.

Rick