jet booat design

jet boat design

Just a design I did up

I would like to build it some day...in the distant future.

set-up for bottom end. but should run in the mid to high 50's. the designs influence comes from the "Century Arabian" built by Century in the 70's and was one of the best designs I have ever seen for a powerboat. light, powerful and fast.

On the lake I grew up on, we had a nieghbour who owned one and we(my buddy and I) plotted hpw to get a ride in it once a year and it was the holy grail of life to get a ride in that!

it did 60+ mph with a 400 hp engine! I think it may have been faster. but hard to say but I thought it ran in the low 70's full throttle.

I based this design on it. added my own touches...



stats:
LOA 16 ft
beam 6 ft at deck
displ.: 1800 lbs. aprox.
draft static: .9 ft
draft dynamic: 4 inches aprox
material, epoxy and two layers Kevlar carbon fiber over 5 lb. density core cell (optional aluminum but at weight cost)

power plant: aluminum block LS1 or other to 450 hp.
pump system- Scott Water jet 8.25 or Hamilton 3 stage (used) or new Hamilton 212 with turbo impeller.
bottom and delta is wrapped with UMVH high density plastic.

The vessel has a Lexan windscreen.

deadrise aprox 12 degree. but could be designed to 6 degree for ultra shallow running.

design intended for use in the Georgian Bay's French, Key, and Pickerel river outlets and river systems, as well as the Bay itself. what is incredible to me is Canada has some of the most amazing jet boating areas in the world but no-one really does a lot of recreational jet boating. we have the potential here to run in world class rivers...yet we don't..??
Just in my area, I know of three incredible rivers that would be jet boat paradise!

 

There's no screw ups in the design of a boat like that, so if you're guessing, you might pay dearly for it. Simply put, get your "centers" arranged for the performance envelop you expect or you'll be swapping ends at high speed, which is a bad hair day to say the least.

 

Morning Par- please explain Centers? and how do I go about getting them?

open minded on this...

 

The CB and CG most notably.

 

Better yet--contact the CBC and inquire if Relics jet boat from the TV production "The Beachcombers" is for sale. This looks very close to it. Possibly they can even supply or direct you to a set of plans. This 70's show was filmed in British Columbia with lead actor Bruno Gerussi.


A yacht is not defined by the vessel but by the love and care of her owner---

 

below are pics of places all within 20 minutes of where I live...what a jet boat heaven it is here.


***I loved that show just for his jet boat...there are many who want that jet boat but there were actually 2 jet boats on the show. someone did buy one of them...not sure about the other...

I like mine better. It is smaller, so it fits into nice small "splits", "rock gardens", "sous holes" etc., rides higher in shallows and is faster, lighter and looks better. I actually don't see much similarity between relics boat and mine.

Bruno is gone now and so is Relic. But they have become legends...
he did have the coolest boat ever...

 

I can get them easily on my program... im assuming they should be on center of the vessel? or should they be back slightly to compensate for the stern mounted engine?

 

I would run another set of strakes between the chine and the keel. On a 12 degree boat, 2 inch by 5 inch angle, full length. This will leave the 5 inch flats with a down angle. Do not form this angle, if 2 x 5 is not available, then cut a 3 x 5 inch extrusion. I am assuming that you would build a jet boat out of aluminum if you are going to go rock crushing
Hard to tell from the picture if the reverse chine run all the way to the back.

The reverse chine and lift strakes will help keep the boat from swapping ends in tight turns, help, not keep it entirely from swapping ends.

A couple of you tubes to look up. Google Mot River Jet boat run, there are a few of them but shows very small boats running some extremely skinny water.
Also, Shotover Jet Boat, out of New Zealand, the original jet commercial operator.
Most people with some experience driving jet boats think they have a handle on skinny water and tight turns, this run through the canyon, opened my eyes. Have owned jet boats since 1979 and built many commercially, but it takes these guys 3 months of training before they can take a paying passenger.
Keep as much weight in the back, to help keep the boat from swapping ends.
Stay away from any fibreglass, maybe you will save some weight but damage hitting rocks will be hard to fix.
Have not used Scott pumps. Only Berkley, Kodiak 3 stage, Hamilton 3 stage 773 and the last while Hamilton 212's. I prefer the 212 for acceleration and the ability to take a few rocks and run them through the pump,
With aluminum you can screw on UHMW plastic to help bounce of rocks

 

I like the Scotts. of course they are outrageously priced. But one look at them and you'll understand why. I prefer a multistage pump but Im no expert- it just seems running rapids you don't want to run a Berk or Jacuzzi.
The 212 is my favorite so far but I think they stopped making staged jets(?)
not sure why...now they have this turbo impeller.
I actually thought I mentioned the UHMW?...musta been daydreaming- yea- I want to put that all over the bottom. just don't want to through bolt it due to the possibility of leaks so I thought about possibly vacuum bagging and gluing a lighter thickness like 1/4 inch to the whole hull?
thanks for the post!
Doug

 

Interesting info on the fibreglass. Not sure if I would consider it.
Bolting UHMW to a hull is not a leak issue. Countersink and drill the plastic, tap the bottom plate, bolt it up with countersunk bolts and put a hard fibre washer under an acorn nut with a bit of silicone and you will not have a problem
Welding aluminum is not hard. A 21 foot jet boat, including tanks would take about 20 25 hours of actual welding time, the rest of the time is fitting the plates, stringers, etc up.
You could learn how to tack weld in about 1/2 hour, do all the fitting yourself, then just hire someone to do the heavy welding.
A note, though, when you stop an aluminum bead, you almost always have a crack from due to the contraction of the aluminum, so when before you restart, take a grinder and put the wheel on edge and cut back the crack to solid weld before restarting
The 773 was a three stage and the 212 has an impeller with a bolt on turbo impeller at the end.
Great pumps

 

Barry's post brings up other questions-(as always).

would a carbon fiber/Kevlar hull be even better at rock running? its impact resistant, abrasion resistant and easy to repair.
I as thinking three layers aside. 6 oz Kevlar+ Biaxial(10 oz.)+ 6 oz CF???
over a 5 lb core? the elongation characteristics would mean the core would elongate at a stress load and not fracture(yield).

so wouldn't this literally bounce off rocks especially with a UMHW covered bottom?

Just thinking out loud here...


- I know AL. is the conventional but some sprints are now using exotics I believe.

 

I do not have any repair experience with Kevlar/fibreglass to comment on this

Not sure if a glue would be available to join fibreglass to UHMW. I would be concerned that the changes in length due to heating and cooling, ie different temp expansion rates between UHMW and fibreglass might be a problem.

I could see sprints using exotics and they are normally not hitting rocks. Hitting a sharp rock (can opener) at 50 mph
that is a different set of circumstances.

 

Ha Ha --Tugboat just kiddin with ya on the similarities -- all them there speedy run abouts tend to look the same to us canvas men. Actually Relic`s jet boat was a turn on for me especially `when the jump a log` stunt was performed. I was baffled for awhile why they didn`t tear up their props.---

A yacht is not defined by the vessel but by the care and love of her owner ---

 

ahh that explains it-- you're a sail man!..hahaha.

think of Tugs and Jet boats as the ultimate in practical yachts...

I had the same thoughts as a kid...knew about boats at a young age so for some reason never questioned it.

But my fav episode was the race that relic had with a prop driven high performance runabout.

Relic used sandbars and things like that to weasel a win out it...


they never show a good shot of the jet setup- and to this day I don't know what setup he used.
I vaguely remember , in fact an episode of it out of the water on a trailer I think being repaired and Nick Adonidas explaining how the jet pump worked to the landlubbers watching the show.

Im guessing ,most of the audience were wondering the same thing about why the lower unit on the hull was not smashed to pieces when he would run over logs and other obstacles- I even guess they probably wrote in letters asking" "how it was the boat could run over a log"? or "how many boats did they go through during each episode"?..."

 

Your probably right about the UHMW not being an issue. But I will say I have seen carbon fiber canoes hit with sledge hammers and nothing- and I mean not even a scratch happens. there is a vid of this too...

I don't think epoxy bonding would be an issue. epoxy can flex slightly and doesn't crack like poly. an epoxy like MAS system is highly flexible. yet bonds incredibly. although its not my first choice of epoxies.

watch this-

https://www.youtube.com/watch?v=7dtk818WSiU

you might be impressed...or maybe not- I think it would be great- BUT the costs are prohibitive...sigh...

so Al is probably the best way to go with for both toughness and cost effective...but check the vid out...


not sure about the can openers...maybe they would tear it apart. But I have my doubts. it would take quite a shot to hole CF... it is stronger than steel.
the only other issue is my work area has only 120 v. right now.

not setup for 220 ...I had to move recently. and now Im stuck for welding service for a while so it may have to be this way if I build it down the road. right now Im just checking it out. I have another project im doing in the meantime.
what have you owned? what was your favorite jet boat?

its weird but Im hard pressed to find a set of sprint plans. seems they are some highly guarded secret. so I am not able to get a set of rugged Sprint jet boat plans... you know of any?
there is one guy out west in BC www.copeboats.com I think. anyway cope boats is the company. you can google it but I don't like the designs all that much. Like mine better...

btw- I watched the vids you sent me- yes- that's what I want to do!! the MOT was great.

here got the guys address he has a website...

Cope Aluminum Boats and Design
594 Maple Street
Qualicum Beach, British Columbia
Canada V9K 1J3
Ph: 250-752-1724

jet boat heaven. very close to my home...see pic below