small jetboat?

[GIVERSOME]

I have been thinking of building a 12'-14' monohull runabout type speedboat. Using arcticat tigershark 3cylinder pwc engine for power along with its jet drive. Has there been any of you who have done this, or know someone that has? I am curious to know if this has been done before.

[mendo]

I would use the Merc jet drive and power.

Quoted from Mercury Webpage:


Mercury 250 OptiMax M2 Jet Drive
Specifications
HP @ Impeller: 250 (186 kW)
Max RPM (WOT): 5150-5650
Cylinder/Configuration: V-6 (60 degree vee)
Displacement (CID/cc): 186/3047
Bore & Stroke (in): 3.63 x 3.00
Bore & Stroke (mm): 92.1 x 76.2
Fuel Induction System: 2-stage Direct fuel injection
Ignition System: PCM Digital Inductive
Alternator: 60 amp/756 watt (belt-driven)
Weight (lbs / kg): 434/197 (engine and pump)
Lubrication System: Electronically controlled, multi-point, variable ratio oil injection
Flush System: Standard
Cooling System: Self-draining
Starting: Computer-controlled, electric with auto-prime and turn-key
Operator Warning System: Engine Guardian - over-rev, overheat, low oil level, low battery voltage, oil system failure, water in fuel, low water pressure, engine sensor failure
SmartCraft: Yes
Pump Type: Mixed flow/high volume
Impeller Diameter (inches): 7.25
Impeller Diameter (millimeters): 184
Impeller Type: 4-blade progressive pitch stainless steel
Trim System: Adjustable plate
Gear Ratio: 1.15:1
Exhaust System: Tuned through-transom with dual mufflers, 3" outlets
Gear Shift: F-N-R with high thrust dual outlet reverse gate
CARB Star Rating: 2

[GIVERSOME]

I am the new guy so thank you for the reply mendo. wouldn't a pwc engine and drive be lighter than a v6 merc. plus the boat isn't going to weigh more than 150 lbs. even if the merc is ideal might it be to big?

[GIVERSOME]

with the pwc engine I will be installing custom dry snowmobile style exaust. This way I wont have to worry about a low shear line and flooding the engine with sea water because the exaust will be high and dry. I tried to pick an engine for dry exaust because I built a 9'6'' 3point hydro with a 25xs merc outboard,and That combo with me a 200 lbs would flood the lower cylinder with seawater. So I am trying to avoid this.

[GIVERSOME]

Mendo back when I was in boat design school one of my projects was a 14' speed boat using a v6 merc and jet drive. I forgot all about doing this until I read your reply. I do not however remember what model mercury it was. Something around 250hp sounds familier though. At the time it did not seam realistic with all that power in such a small boat. Now though it sounds like a real good idea. I am still playing around with the idea of the pwc engine to.

Again is there anyone that has tried the v6 merc and jet drive combo in a small speed boat, or tried the jet ski engine and drive. I want to build one so any pointers would be appreciated.

[GIVERSOME]

If I wanted a more efficient setup using the pwc engine probably using a hull in the 10' range would be better?

[Iceout]

Giver,

I'm going about the same type of project. It's a 13' Bullet, powered until last week by a 75hp Evinrude, but still not enough. If you plan to run in the open water, you might want to rethink that jet drive idea. I've concluded that the jet drive is not the way to go for mine, consideriing how much thrust is lost when breaking the surface on a jet ski or small jet boat (just when things are starting to get exciting). I've got a few ideas rattling around here, like a surface drive (see Pulsedrive's Model 1000).

For your idea, there's a Merc 260 jet on a little thing called a Mouse on this site in several places (85 MPH they say, but not in the rough, me thinks).

Iceout

[150aintenuff]

THat 250 optimax Engine will push 22' hEAVY gauge Northwest JET SLEDs to 55mph, in properly built 14-16' speedboat you could see 80+ EASY

Use a 10-14 degree bottom and a Pad(FLAT) leading up to intake to ENSURE a clean path of jet intake water and it is VERY possible to build it.

Good luck and WE all want pics after its built

[rockdamage]

http://www.glen-l.com/jetski/jetjon-index.html

[xp205]

the imfamous mouse boat is my uncles. it started with a 2 cylinder jet ski motor, but then he put a 200 merc power head on a right angle drive to a jet pump and it moved. he then put a 260 merc on it and the boat screws. the only problem is it can't handle any chop at high speeds. the boat has been recorded by gps to do 80mph.

[Bushmen]

How did the mouse boat do with a jet ski motor ??????

[Bushmen]

Guys I just got a 650cc kawasaki jet motor from a jet ski.
I keep the bottom part of the jet ski just in case I wanted to use it.

I need to short cut the process as much as possibly as its hard on my back to do alot of work.

first how much HP is the 650cc motor????

Is their a light weight alum or glass boat I can buy and cut up to make it easy and very light.I was thinking about the mouse boat but maybe too heavy.

I saw a 8 or 10 foot alum row boat done that went well light small.

any suggestions or picks

I like speed so I want to keep it light.what the limit on weight of the hull using a 650 cc Kaw and how fast will it go.

I have a very cool deep vee boat with wings on the back like a B-24 Bat boat but it is 13 feet long.weight around 150lb.Can you use this process on a vee?????

Thanks Guys :D

[WATERWINGS]

"all that power in such a small boat"

What are we thinking??

I think we all need to go back and get 90 HP motors cause our boats are to small and light for that much power:eek: :D

Welcome aboard Giversome !

[F250]

I was thinking to put a 650 kawasaki jet in to a 3 meter rib

[tuffjet]

Check out www.tuffjets.co.nz (http://www.tuffjets.co.nz)

Is a small two seat plastic jet boat made here in New Zealannd. Is powered by a Seadoo 800cc engine they are quick, lihgt and slid across rocks so make great hunting or adventure boat.