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Old 03-10-2011, 16:27   #16
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

cat man do,

317 lbs, 96 volt LiPo, 14.4 KWh
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Old 03-10-2011, 16:53   #17
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

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cat man do,

317 lbs, 96 volt LiPo, 14.4 KWh
And the motor?

Battery weight alone is 317lb = 143kg
That'll be some dinghy needed to carry that sort of weight + passengers.
And you may need to upgrade your davits
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Old 03-10-2011, 17:03   #18
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

Yeah, true, 44CC, your application / lifestyle requires high speed to get up those rivers and coordinate the tides. The final choice is all about the specific application. Why do you require an inflatable? You have davits and plenty of room for a rigid?

The triple 20 HP outboards would be great in terms of spare parts stock. Our twin 8 HP outboards are occasionally too small and and we are considering a change. But not DOWN to triple 3.5 HP!!

In the meantime, we learn more about patience, planning and sailing.
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Old 03-10-2011, 17:07   #19
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

Lower drive from a 50 hp outboard, electric motor itself weighs 33 lbs. The picture is of a Catalac currently for sale, I'm not ready to buy yet. Going to set up the tender first and hope LiPo batteries continue to drop in cost when the time comes to purchase and refit something like a 12 meter Catalac.
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Old 03-10-2011, 17:36   #20
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

We have an 11 foot Dux Catamaran dingy. We bought it used from a serial Dux owner. It folds up and does store on our boat, but it ia BIG, HEAVY boat to deal with. For an engine we have a 15hp 2stroke.

We have had it a year, and not had to use it on anything other than light chop. It does kick up a little more spray then a v hull hard bottom, but we could not use one of those, so it is ok. We may be going south this winter, so perhaps we wil get more experience in different conditions.

I would rate the build quality as "fair". Actually, I am hesitant to rate this, as we did not own the boat from new. It was a year old when we bought it, used by full time cruisers on a catamaran. Some of the spray defectors (kinda like rub rails) are coming unglued at the ends. There is some slight peeling of attachment point patches. The fabric does seem to be much heavier and thicker than most PVC boats.

It tracks wonderfully when towing, due to the hijackers.

Chris
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Old 03-10-2011, 17:36   #21
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

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Lower drive from a 50 hp outboard, electric motor itself weighs 33 lbs. .
Ok, so by the time you do batteries, motor, props, leg or shaft, cabling etc etc you will be in the vicinity of 370 pounds = 170 kilograms +- just for the propulsion

I would imagine to carry that weight of propulsion plus passengers you will be needing a rather substantial dinghy, which, does not really fit in with your
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My need is for a very efficient minimum wetted hulled "anything" that can ride the davits in all sea conditions
comment.

Quote:
The picture is of a Catalac currently for sale, <snip>when the time comes to purchase and refit something like a 12 meter Catalac
I also would think that a catalac 12 may not be the vessel for carrying such a substantial dinghy as heavy weights in the far extremities of a multihull are not usually a good thing.

FWIW, I am probably looking at a 3.2m aluminium dinghy, with a 10hp outboard and the weight for this including 20l of fuel will be about 110kg, and I have my concerns about its weight.

And that's on the back of a 50ft cat.
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Old 03-10-2011, 17:45   #22
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

deckofficer;

While I applaud your consideration of electric for the dingy, I think your proposed setup would be a mistake. If you need a planing dingy, and are cruising, there is nothing better than the density of gasoline to zip you along!

Chris
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Old 03-10-2011, 18:20   #23
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

I plan on strapping the 3.2 volt cells as 6 seperate blocks, each weighing about 53 lbs and removable. Good old velcro on the bottom of each bank and matching velcro on the flooring slats.
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Old 03-10-2011, 18:43   #24
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

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deckofficer;

While I applaud your consideration of electric for the dingy, I think your proposed setup would be a mistake. If you need a planing dingy, and are cruising, there is nothing better than the density of gasoline to zip you along!

Chris
I agree. I have an electric dingy, which is basically just a slightly modified trolling motor with an AGM battery in a box with a switch and a fuse. It's killer for my application, which is short trips in protected waters. But electric is all about slow efficiency. And not having to store the motor upright. Didn't really realize what a nice bonus that particular feature was...

I should also probably throw in that I have converted my auxiliary sailboat to electric power as well, and that most folks I know kind of consider me a bit of an electric boat zealot. Please don't think of me as one of the "you're going to die if you use electric propulsion" crowd.

That being said, I fail to see the advantage in a 300 lbs. battery pack in a dink. A Honda EU2000 generator only weighs 54 lbs. with a full load of fuel and oil. The EU1000 is just 33 lbs. Throw in another 10 lbs. worth of jerry jug, and you could drive that dink for hours. Just leave it on the boat for short trips. The traction bank for my 30' sailboat (4x4D AGM) weighs 516 lbs (not including wiring). At the rated output of the genny (1.6KW) I can push my boat at 3.5kn. Can you talk a bit about why you chose that particularly large bank?

The energy density for batteries just isn't there for economical and practical large banks. We just still can't beat gas or diesel for energy density.

As an electric boating enthusiast, I'm always interested in other people's boats. Can you describe your performance numbers (watts to knots) and build a bit please? If you're modifying an existing outboard leg you must have thought through these suggestions already as a DIY kind of person. I'm curious as to the reasoning for the choices you made.

JRM
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Old 03-10-2011, 19:06   #25
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

We are using one of these as our tender.... http://takacat.com/11.html
Its nice and light,hangs off the davits nicely and gets up and goes quite nicely.
Matt
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Old 03-10-2011, 19:32   #26
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

Matt,

I'll get back to you, your link has me interested and I need to research what looks like a great tender, thanks for the link. I have to remember to use search engines from Australia and South Africa, as both are way ahead of the US on modern tenders.
I've come back in time to edit this post. 3.3 hp will plane that boat of yours, now that is efficient. Please tell me all you can of your experience with this great little tender. This company even gives you a choice (at about 2X the price) of PVC or Hypalon. This is the one that looks promising.

JRM,

I used to work in the oil industry, so even though their product packs more energy per mass than I can store in current LiPo offerings, that is my goal, first as proof of concept for the tender, then scale up for a refit of an older, heavier, cruising cat.

Bob
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Old 03-10-2011, 19:39   #27
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

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Matt,

I'll get back to you, your link has me interested and I need to research what looks like a great tender, thanks for the link. I have to remember to use search engines from Australia and South Africa, as both are way ahead of the US on modern tenders.

JRM,

I used to work in the oil industry, so even though their product packs more energy per mass than I can store in current LiPo offerings, that is my goal, first as proof of concept for the tender, then scale up for a refit of an older, heavier, cruising cat.

Bob
I'm intrested in how you do but that is a heavy undertaking.
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Old 03-10-2011, 21:03   #28
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

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Matt,
JRM,

I used to work in the oil industry, so even though their product packs more energy per mass than I can store in current LiPo offerings, that is my goal, first as proof of concept for the tender, then scale up for a refit of an older, heavier, cruising cat.

Bob
I understand the desire. But a large part of going electric is changing your mindset about speed. As a general estimate, each knot of speed doubles the power consumption (for displacement hulls). I can't speak to planing other than what I read, and it's not very common because the range is extremely limited due to the large power requirement. As the Torqueedo finds traction, I expect more planing data to come out. But we're talking light boats, not something trying to plane 300+ pounds of batteries alone.

Your location says southern California. I'm basically in southern California also. There are many electric boaters here, many much more knowledgable than I. Also, if you haven't already found it, the yahoo groups electricboats list is a great resource.

I'm looking forward to following your progress. Please keep us posted.

JRM
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Old 03-10-2011, 21:21   #29
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

There was a dinghy years ago called a sportyak.....I even did some mild whitewater in one.
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Old 03-10-2011, 22:49   #30
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Re: Anyone Using a High Performance Cat / Tunnel Hull Dinghy ?

Matt directed me to a Aussie tender that claims a 3.3 hp motor can plane it out. That would mean less than 3.3 hp to hold it on plane, and that is really good. I feel an electric, even at the same low hp could bring to plane even faster due to the full torque available at zero rpm. As far as weight goes, I'm a singlehander, and at my age more than likely will be next time I'm cruising. These boats all have 900~1300 lb payload for the 12 to 13.5' models, so the 317 lb battery weight should not be an issue. Unlike gas or diesel engines, an electric motor capable of 40 hp will still have its efficiency at all outputs. The reason for an overkill 30 KW motor is I have already picked up one of these motors, for the tender and if it proves out, two for the cruising cat. All will accept 96 volts for full output, and as you all know, if you run a higher voltage you run lower amps and have less line loss in cable heat. And then there is the "hot rod" aspect of my warped personality, can you even imagine how one of these light cat/tunnel dinghies would respond to full 30 KW output ?

Bob
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