T-Pain Is On A Boat: Re: [Electric Boats] Re: House boat conversion

Monday, January 30, 2012

Re: [Electric Boats] Re: House boat conversion

excellent idea and post Bill, to try towing with 10hp as a test. the only thing I'd call iffy about it is need of a low pitch "grunt prop" on it to actually do a good test with.

my 10hp long shaft honda 4 stroke was built and propped to be a big sailboat pusher,

might be closer to appropriate for testing like that. (maybe have a sailboat tow ya?)

I might have some sympathy for the 4hp engine that might not have had a chance to spin up to produce a little power.. but hey I wasnt there to see it happening either, and can only suspect it being the situation with the little engine struggling to even get to 3k rpm..

theres some with 4-5 pitch high thrust props too of course, are hard to drag down!

I'm pretty impressed with a 30lb trolling motor moving your houseboat at 1mph,

thats a heck of a load! I dont know if it'd be helpful or not, but over at "hannu's boatyard" site he has a whole bunch of his little rowboats graphed out "speed vs resistance". its different for bigger heavier longer wider etc, but maybe still relevant too for low speed ballpark calculations. the other basic ballpark calculator I like a lot is:

http://go-fast.com/boat_speed_predictions.htm

sure its intended for planing speedboats, but its fairly decent about things like "900lbs with 0.35hp and a hull constant of 225 (default and maybe good rep of displacement)..

equals ______ potential mph speed". knocking about 15-20% off, is pretty fair.

next curiosity.. would a parabolic dish mirror heating a pressure vessel boiler to a small steam engine be maybe more productive go-go than photovoltaic to electric motor power?

theres a few youtube video's exploring that, solar steam boiler to engine to generator, the guy is making some pretty decent Kw from it! sunshine dependant of course, but solar boiler to steam engine would run for free on windless days when sailboats cant..

theres a video of a kid who coated a TV dish with small bits of mirror, it was igniting everything he held in its sweet spot within seconds.

--- On Mon, 1/30/12, Steamboat Willie <stmbtwle@yahoo.com> wrote:

From: Steamboat Willie <stmbtwle@yahoo.com>
Subject: [Electric Boats] Re: House boat conversion
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Date: Monday, January 30, 2012, 1:42 PM

I can see why a lot of them don't want to help; a houseboat is a big boxy contraption (I have one about your size) and it's going to take a LOT of power to move it very fast and a lot of BATTERY to go very far.   Just for a lark one day I tried to push mine with a 30# electric trolling motor; I got ONE mph average going both ways in a dead calm, so yes it's possible. For comparison on the same day I tried a 4 hp gas outboard; I got TWO mph under the same conditions.

For starters I'd borrow a dinghy with a gas outboard (10 hp or so) and see just how fast you can push that houseboat.   That will at least give you an idea of how much horsepower is needed to go X mph.   It's a rough guess but it's a start. Some one of the experts on here can probably take that number and give you an estimate of how many KW of motor it'll take. Then you have to figure how far you want to go and how much battery power it'll take to get there. Then IF you're still interested you can start comparing different types of drives.

Every time I buy diesel I dream how nice it would be to install an electric drive and push my boat with solar power, but every time I do the math it gets pretty discouraging.

Bill