Hi Eric, thanks much for the reply. The barge front end would definitely be an issue if the water entry of the hull wasn't so gentle. It is a very shallow angle though, so I don't anticipate a problem as long as the waves are 1.5' or less. Somewhere between 1' and 2' wave height I'll start knocking the "bow transom" into oncoming waves, greatly hampering forward progress. Large boat wakes aside, 2' waves on the rivers I'm talking about are not the norm. In the types of conditions I'm going to be operating in, < 1' waves are to be expected.
As far as the boat settling fore and aft, we should discuss that because it's been a theme of the feedback so far this morning since posting the pics. By my calculations, at 12k displacement and perfect COG, if I (a touch more than 200 lbs) were to move from the center of the boat and go stand on the rear transom, the stern would settle < 1/3". I'm quite willing to accept that. Stepping out onto the bow would cause the front to settle a little more because the COG is about 2.5' aft of the center of the boat, but it wouldn't be much more. Less than 1/2", I believe (though I didn't run the numbers on that yet, so it could be a bit more... but *definitely* less than 1").
All that being said, it's difficult to know how wave action will set the boat to pitching, or how quickly she'll settle down once started. That's definitely a bit of a gamble on my part, but so far I haven't heard anything that makes me want to avoid that gamble enough to redesign the boat. :)
Side winds are indeed a real possible issue. I do have some experience piloting larger houseboats, and side winds really, er, "blow". ;) The height of this one is a compromise, higher than I'd like for exactly the side wind reason, but lower than I'd like for living concerns. Note that one will be forced to duck no matter how they enter this boat. In this particular case I'll probably just have to pick my weather window and go out when the wind is fairly calm. Fortunately it's not overly windy here, and for me just being on the boat is a lot of fun, even if I'm not moving it around on the river.
I'm still interested in hearing someone's thoughts about the ideal power, prop size, prop rpm, and prop pitch for this boat. 27' waterline. 12k lbs. Fairly easily driven in calm conditions, but heavy.
Still hoping for a 48v system, too.
Thanks,
-keith
--- On Fri, 5/4/12, Eric <ewdysar@yahoo.com> wrote:
> From: Eric <ewdysar@yahoo.com>
> Subject: [Electric Boats] Re: concept for an electric houseboat
> To: electricboats@yahoogroups.com
> Date: Friday, May 4, 2012, 11:35 AM
> Hi Keith,
>
> There might be reasons that you've never seen a boat design
> quite like what you've come up with.
>
> With a barge front end, no bow taper, I doubt that a 10kW
> outboard could push the boat to hull speed (6.5kts) even at
> full power. The full rocker will mean that the boat
> will settle fore or aft when you walk from one end to the
> other, maybe entertaining at first, but I wouldn't want to
> live like that. You need more set bouyancy at the ends
> to create a stable platform.
>
> Personally, I wouldn't be worried about driving into a
> headwind, I think that your design lasks the power to deal
> with almost any sort of cross wind. Your boat has a
> huge side profile. Think about it with a regular ICE
> outboard. I wouldn't think that a 20hp motor would
> provide safe navigation in anything but very calm
> conditions.
>
> But you did say that this is a liveaboard, and as a floating
> home, it's seaworthyness is not really an issue. Most
> of the liveaboard houseboats in my area can barely move
> under their own power and rarely move at all. So if
> you boat has just enough power to move slowly from one place
> to another, picking only the most benign conditions, then
> you should be fine. If that is all that you want to
> do, then your design should be adequate.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> "It's easy to make something that looks like an airplane,
> it's much harder to make one that can fly."
>
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