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nzjetboating.com Forums => Projects => Topic started by: darcy87 on August 14, 2020, 10:59:08 AM

Title: Jet skiff??
Post by: darcy87 on August 14, 2020, 10:59:08 AM
Hi Lads,

Been a while since I posted on here. Just wanted to spitball an idea for a smallish shallow water fishing vessel thingy. The plans are for plywood but I wanted to build it in alloy. The specs are LOA 4.15m, 1.27m beam. I've got a 700 yammie and pump laying around, would that be enough grunt? Not looking for a rocket ship.

Any input would be appreciated before I jump headlong into it.

Cheers

Darcy
Title: Re: Jet skiff??
Post by: Kakapo76 on August 14, 2020, 14:07:00 PM
Theres a bunch of guys in the USA who have converted boats they call Jet Jons or Jon Boats- on you tube there a few basic builds- very similar hull shape to what you are proposing- might be worth a look. Weight distrbution will be key- might work best with a cnter console style layout similar to a rib?

https://www.youtube.com/results?search_query=jet+jon
Title: Re: Jet skiff??
Post by: darcy87 on August 14, 2020, 15:01:02 PM
Thanks Kakapo, I had a browse through those vids, looks like they go alright. I was thinking centre console..... something kinda like this.
Title: Re: Jet skiff??
Post by: Kakapo76 on August 14, 2020, 16:59:23 PM
I would go jet ski gear- buy a ski and rip it all out and make a custom intake/ grill plus asp adaptor. If you are going to go that sort of boat be warned anything more than six inch chop and that hull will slap  and pound like .... well you can work it out  O))))

If you are looking for plans- look to the wooden boat community, they do all sorts of skiffs out of plywood which behaves in a similar way and most boats can be cut out of flat sheets.

Like this one: https://www.boatdesigns.com/Flats-Flyer/products/740/ I would scale it down to whatever size you wanted.

I reckon it would go great with a 250 kawasaki in its current form or a smaller engine if scaled appropriately.
Title: Re: Jet skiff??
Post by: darcy87 on August 15, 2020, 10:17:54 AM
The mighty 701. Dragged it out from its hiding place, cleaned off 5 years worth of dust, robbed the battery from the mower, tipped a bit of fuel down its neck and viola!
Title: Re: Jet skiff??
Post by: spinner on August 16, 2020, 20:45:47 PM
Do you know how important the length of rubber hose comeing from the exhaust is? This goes to a muffler box in the ski.
 I am planning on using the same engine and trying to figure out how to run the exhaust.
Title: Re: Jet skiff??
Post by: Jeff B on August 16, 2020, 20:50:28 PM
I believe the length of hose/pipe between the exhaust chamber and water box is not terribly important
Title: Re: Jet skiff??
Post by: Warwick Marflitt on August 16, 2020, 22:47:14 PM
Check out this designer's award winning design

https://bandbyachtdesigns.com/marissa-eco-18-plans/
Title: Re: Jet skiff??
Post by: darcy87 on August 16, 2020, 23:12:20 PM
Spinner, I wasnt sure about the pipe length so I'm glad Jeff B shed some light on the matter (thanks Jeff). What kind of ship is your 701 going in?

Warwick, that's a nice looking boat.
Title: Re: Jet skiff??
Post by: Jeff B on August 17, 2020, 07:25:22 AM
The 701 yamaha might struggle to push it?
What will the weight be?
Title: Re: Jet skiff??
Post by: darcy87 on August 17, 2020, 08:10:45 AM
Jeff, the plans say it comes out around 150 lbs(in plywood) so that's about 75/80kg. I was thinking mainly 3mm Ali for most of it, maybe 4mm for the bottom.  What do you think?
Title: Re: Jet skiff??
Post by: Jeff B on August 20, 2020, 06:32:51 AM
I guess it's still quite small, only 1300 chine width.
But I think it will be quite a bit heavier than 80kg?
I think closer to 250kg complete with engine, everything set up?
The 701 should push it ok?
Title: Re: Jet skiff??
Post by: darcy87 on August 20, 2020, 10:29:19 AM
Yeah I agree, the 80kg estimate was in the plans and for the hull weight only (and in plywood).

I'm going to have to go with the 701 because I don't have anything else and on a bit of a budget.

Probably shouldn't start building another boat then eh? Hahahaha
Title: Re: Jet skiff??
Post by: troutcatcher on August 20, 2020, 20:04:33 PM
I have a 3.6m centre consol aloy boat a copy of the Riddler , powered by a 90 hp sport jet. I have built mine with fold down dash and seats to transport my quad on the top
Title: Re: Jet skiff??
Post by: troutcatcher on August 23, 2020, 15:46:40 PM
Found 2 more photooos taken on the rakaia river
Title: Re: Jet skiff??
Post by: darcy87 on August 23, 2020, 17:58:59 PM
Thanks troutcatcher. I found your build thread and had a good read. How do u find the performance of the sport jet? Anything you would UK old have done differently?
Title: Re: Jet skiff??
Post by: troutcatcher on August 24, 2020, 18:59:04 PM
Planes about 23 km per hour and flat out on a lake 62kph. Toatal weight 320kg and withplastic 700 wide on the bottom , no trouble to shift off the shingle. Time to use it a problem, only did 25 minutes last season. Hope this one is better