Any Jet Boat experts on the forum ?

[Happy]

Here's pic of boat I acquired recently. Has Holden V6 and single stage unit Cavitates when you boot it off the mark
Also takes honks to get up but once up its awesome I wonder if too much weight in rear as nose loves bein up in the air
Thinking relocate batt plus fuel tank to front plus some fixed trim tabs

Anyone have any other ideas or experience all new to me it's real good on gas and has no vices except fast planing speed and long time to get it up there and get the nose down it comes off the plane real quick as well
I reckon mtr should have been nearer to the front but can't change that

Bugger can't upload pic here's a link to some

http://www.nzhuntingandshooting.co.n...jet-boat-4468/

[Toby]

I'm not a jet boat expert but swap the Holden for a Ford

[Happy]

I'm not a jet boat expert but swap the Holden for a Ford

Right on to it

Then it won't go round corners and I'll have the Ford owners tendency to want to stab people all the time

[veitnamcam]

Sounds like wear ring in jet unit worn or impellers damaged.
Get someone who knows what they are looking at to look at the pump .

Sent from my GT-S5360T using Tapatalk 2

[optio]

I'm no expert by any means, but check intake grill under boat may have stones or something jammed in grill if so use screwdriver to spread bars stones will drop out if OK check impellors as vietnamcam suggests.

[outdoorlad]

First thing to check is that the grill is clear of stones, then shine a torch up the nozzle and check the impeller clearance to the wear ring, the tips (trailing edges) may need building up.

[Barny Rubble]

Looking at your photos it looks like your boat is a J31. These were a Marlborough Marine Dart hull that were usually out board hulls but some were used by Hamiltons as jetboats.
These hulls are deep v and are around 20 degrees so are more suited to deeper water than shallow water.
Because they are a deeper v they will need a higher speed to plane and because they are a short hull as well are sensetive to weigh/load.
The Holden 3.8 should be more than enough power but as it looks like a colorado single stage you are at or over the top end of H.P. for this unit.
I am guessing that the previous power unit was matched to the unit and now that the 3.8 has been installed the extra power combined with a worn unit is causing the problems that you are experiencing.
Idealy a Holden 3.8 would have a 2 stage 7.5 inch hamilton unit behind it to efficiently use the available power but you could get away with a single stage providing you got the correct impellor and nossle to suit and the rest of the unit is in good order.
You could get the bow down by shifting weight forward or pointing the nossle down further but watch out for tendency to bow steer.
Also check the bottom with a strait edge on a fore and aft plane to make sure that previous repairs have not altered the integrity of the planing area.

[Dougie]

Right on to it

Then it won't go round corners and I'll have the Ford owners tendency to want to stab people all the time

Hahahaha

Good luck with the boat, Happy. I didn't realise that you could really get jet boats with that shaped hull.

[Twoshotkill]

Hi Happy where in the Waikato are you??
I have a good mate in Taupo that is a jet boat freak and is pretty clued up on them. Him and I are in the Jetsprint Circuit for this season
I can line you up with him if you want but you may have to drag it to Taupo for a day. our first race for the season was last week.
Flick me a PM and i will see what i can sort out.

[7mmsaum]

Hi Happy where in the Waikato are you??
I have a good mate in Taupo that is a jet boat freak and is pretty clued up on them. Him and I are in the Jetsprint Circuit for this season
I can line you up with him if you want but you may have to drag it to Taupo for a day. our first race for the season was last week.
Flick me a PM and i will see what i can sort out.

Are you able to post up any videos of your races twoshot?

[Twoshotkill]

Pics are the best i can do for now.... some idiot put me in charge of the GoPro camera and we only got one race filmed (plus 25 mins after the race) then the batery went flat.
It is on a laptop in Taupo and i cant get a copy for another couple of weeks and its too big to send. I will put it on here when i get it!

[Twoshotkill]

[Toby]

That boat is wicked, If death himself had a boat that would be it.

[Happy]

Have removed steering nozzle plus the short fixed nozzle. Steering nozzle has T3 Embossed on it. When you use a torch and look up into the unit the impeller you can see is mint as. There are no bits missing on the edges and to me it's near impossible to spot the clearance between housing and tips and there are no rubbing marks at all either It's Colorado exp 30 single stage unit

Any point talking to the manufacturer in CHCh to see if there is an impeller to suit the current horsepower but then how hard to remove the unit and get it fitted


This is the exact rear parts it has

http://www.trademe.co.nz/motors/boat...-548738795.htm

[Happy]

That boat is wicked, If death himself had a boat that would be it.

Oh you wouldn't suggest that they put a Ford engine in it to make it go better then. .??