Runabout, powered by PWC

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Re: Runabout, powered by PWC

Post by tech_support » Mon Sep 22, 2014 3:31 pm

The jetboat is featured in this month issue of Boating Magazine :D Some pictures from the photo shoot.........

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We will also be putting the boat up for sale. Anyone interested in her can contact me.... shine@e-boat.net



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Re: Runabout, powered by PWC

Post by tech_support » Mon Sep 22, 2014 3:37 pm

The reverse hood on the Kawasaki had a plastic lever to hold the hood in the up position. I made this lever with a locking pin to do that same job :)

made from scrap teak and epoxy coated. A stainless hex bolt is set in epoxy into the block of teak, then a couple washers and a lock nut. Simple, effective, and nice looking.

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Re: Runabout, powered by PWC

Post by tech_support » Tue Sep 23, 2014 3:43 pm


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Re: Runabout, powered by PWC

Post by swifty » Thu Oct 09, 2014 9:32 pm

jacquesmm wrote:
AtTheBrink wrote: I would not put the jet unit on a flat bottom boat. It has been done, it works but it ventilates.
Bottom line: it could fit most of our boats except the flat bottom ones.

I am new to this forum ready to take the plunge into building a powerboat. hope i may ask a Q here.
i was wondering if the rb14 is able to get a jet engine. in the study plans
it says:
It's an old fashioned vee hull that ends up with almost no dead rise
.
so does it have just enough dead rise for a jet or not?
i would like a 14(maybe 12-16) boat with a jet engine. seeing as that is the cheapest propulsion available.
donor jet sis can be head for 1000-2000 euros( 100-120 hp)

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Re: Runabout, powered by PWC

Post by ks8 » Thu Oct 09, 2014 10:01 pm

Hello swifty.

Here's from Jacques, back on Feb 1, 2013...
From the specs, I guess we will end up with a light boat about 17' long styled like the RB16 but wider and a much more powerful hull.
So I'm guessing this particular design is something more suitable than one of the RB designs, *wider and a much more powerful hull*, for powering with a *re-purposed* jetski jet. I haven't been following if the plans are available for this one yet, but it looks like it would be the better option than modifying an RB, especially since it has been prototyped and sea trialed already, with good reports. See the craig's list listing while it is still listed. :)

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Re: Runabout, powered by PWC

Post by swifty » Thu Oct 09, 2014 10:24 pm

ks8 wrote:Hello swifty.

Here's from Jacques, back on Feb 1, 2013...
From the specs, I guess we will end up with a light boat about 17' long styled like the RB16 but wider and a much more powerful hull.
So I'm guessing this particular design is something more suitable than one of the RB designs, *wider and a much more powerful hull*, for powering with a *re-purposed* jetski jet. I haven't been following if the plans are available for this one yet, but it looks like it would be the better option than modifying an RB, especially since it has been prototyped and sea trialed already, with good reports. See the craig's list listing while it is still listed. :)

but still think 17 is to long. bit wider is also not really what i want. in a perfect world it would be the 12 or 14. with maybe a somewhere around 70 hp jet.

or maybe scale back the JA17 by 10% makng it a 15.3 :D

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Re: Runabout, powered by PWC

Post by ks8 » Fri Oct 10, 2014 2:12 pm

That I don't know about. I simply wanted to point out that there is a design that they have prototyped already, and after trials, have said, basically, this design works in this configuration.

Maybe Jacques or Joel will clarify what other designs are suitable candidates for a 70 hp jet drive adaptation. Remember, without actually testing it first, it might be difficult to definitely say what will work with what, when it comes to adapting that sort of drive to an existing boat that was not specifically designed for it. And with that, I'm in over my head and will back out. I hope your project comes together in a way to meet all your best expectations. :)

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Re: Runabout, powered by PWC

Post by jacquesmm » Fri Oct 10, 2014 2:48 pm

swifty wrote: so does it have just enough dead rise for a jet or not?
Apparently it does, see the video links above. :D
We launched the boat several times to test some small stuff, Joel has used her a couple of times on the week-end and some of our builders have been in her. She goes about 50 mph, no aeration, no cavitation in turns, no porpoising. great design ( I was lucky :wink: and Joel did a great job building a fair hull with the expected weight).
I must have written the words "almost no deadrise" at the very beginning of the hull design process. She has about 8 degrees deadrise at the transom. I remember starting with an old fashioned type hull with variable deadrise and ending up with more modern constant deadrise lines (=parallel buttocks) to use all that 140 HP and to match a generic jetski hull. It worked.

i would like a 14(maybe 12-16) boat with a jet engine. seeing as that is the cheapest propulsion available.
donor jet sis can be head for 1000-2000 euros( 100-120 hp)
The plans for the boat that Joel built will be available within 2 or 3 weeks. The boat is designed since 6 months but never properly drafted. I'll call it the JA18. I just finished the outboard version, it is listed as RB18.
You could use the RB14 or RB16 hull but it will be a little tricky.
The reason is that the RB12/14/16 have a variable deadrise (the buttocks are not parallel to the keel but the jetskis all have constant deadrise around 12 degrees. The rear part of the donor bottom will stick out more than on the JA.

Sorry if I can't explain it better.
In other words, constant deadrise hulls (jetski and boat) will match smoothly even if the angle is a little bit different. the cuts for the jetski in the hull will be parallel to the keel. The intersection is a rectangle, see the pictures of the cut. The intersection between the jet constant deadrise and the variable deadrise bottom of the RB14/16 will look like a wedge.
It can be done.

Do a search with the words "constant deadrise hull jet drive" and you will find comments by Sponberg. I use less deadrise than he does, I'm stuck with the jet ski bottom but the idea is the same.

How about waiting for the publication of the JA18 plans? You can always scale them down.
Jacques Mertens - Designer
http://bateau.com

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Re: Runabout, powered by PWC

Post by jacquesmm » Fri Oct 10, 2014 2:50 pm

No problem going on with this discussion but I may decide to split the topic. It will be easier to read and search.
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http://bateau.com

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Re: Runabout, powered by PWC

Post by tech_support » Fri Oct 10, 2014 3:21 pm

Its very difficult to get air into the pump, very hard to get cavitation. The section of jet ski hull protruded enough to make a pad and the water is clean going into the pump at all but the very sharpest angles. I have to say that I expected it to be a performer, but I was surprised how well she handles.

If you want to put a jet pump in a runabout, this is the design to go with, hands down, no second choice :D

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