Jet 45 on a 16' harbercraft

[Deano1234]

Does anyone know what hieght to set up a jet 45 in relation to the bottom of the hull. Reason I ask is the motor sends a three ft spray up right at the back of the boat so I'm wondering if I can raised the motor. But I'll have to drill new holes so I want to be sure before I start.

 

[tashasdaddy]

Re: Jet 45 on a 16' harbercraft

use the blue post reply, post some pictures of the set up and the boat. type what you want, then scroll down to manage attachments, clik, and you can upload from computer or hosting site, like photobucket.

 

[longshanks]

Re: Jet 45 on a 16' harbercraft

hey Deano

I'm running that same motor on a 15' tunnel hull. Mine also sprays up some water while running, I think it is fairly normal, from the water hitting and deflecting off the shoe. Mine is set up to be approximately even with the top of the tunnel.

Assuming your hull is flat, or slight vee, most that I've seen have the leading edge of the jet shoe set up approximately level with the bottom of the transom. Any higher than that, the motor may cavitate, as it ingests air.

good luck

longshanks

 

[Deano1234]

Re: Jet 45 on a 16' harbercraft

Thanks for the info, I went recently got some info from the factory that built it and that is what they said. To have it flush with the bottom of the Boat, It is about an 1.5 below right know so it has got to be robbing lots of power. I'm going to drill new holes and raise it this week and see how it runs after that.

 

[longshanks]

Re: Jet 45 on a 16' harbercraft

good luck with that Deano. Mine has been a GREAT motor so far, although it sure is noisy. I can hear it coming from miles away. I'm told that the stainless impellor makes it even louder, but I haven't got one yet. I am getting around 3-4gph fuel consumption, on a 15' sled, and couldn't be any happier with the motor, unless it were quieter. I suspect this may be because the boat is a tunnel hull, and the motor is mounted fairly high on mine. I have run my boat across bars in the past, and the tunnel serves ok to protect the jet shoe from damage. Hope your's works out ok.
cheers
longshanks

 

[Deano1234]

Re: Jet 45 on a 16' harbercraft

Hey, So I raised the motor flush with the bottom of the hull, it got rid of the spray and I gained 8 km per hr (by gps measurements) I also took it out into some nice sized waves from wake boats and it didn't cavitate once. Moving it should increase my fuel range, But I still haven't figure out the gph. Maybe this weekend I'll get on the water and burn some fuel.

Deano

 

[longshanks]

Re: Jet 45 on a 16' harbercraft

that's all good Deano! I'm interested to hear how fast your rig goes. Mine tops out around 45km/hr, and I think it would go faster, if it weren't for the fact that it is a tunnelled hull, and it's heavy (3/16" bottom, and skookum build). Check out www.outboardjets.com, if you haven't already, for some useful information on OB jet pumps. I am planning to do some additional mods to my intake, that are supposed to increase efficiency. Have fun burning gas, and let us know how it goes.
cheers

 

[Deano1234]

Re: Jet 45 on a 16' harbercraft

45km Thats pretty good I was only getting 33km until I lifted it and know my max is 40km, What type of mods can you do to these jets/ intakes to get more power.

Thanks
Deano

 

[longshanks]

Re: Jet 45 on a 16' harbercraft

hey Deano... check out www.riverjetmagazine.com. Go to the forums, and look up the thread on jet-eze products. I haven't tried these yet, but I am in the process of making some intake fins.

The main thing you can do to improve performance out of your jet, assuming it is mounted properly on the hull, is to shim and sharpen the impeller. Here is a tutorial: http://www.snyderboats.com/30minPM.htm

make sure you leave enough tolerance between the impeller and the sleeve, or you can get into a situation where the motor won't turn over. I came across a guy that had this problem this weekend.

If you haven't tried shimming the impeller yet, you may be surprised at what in increase in speed you can get from it.

Is your jet as noisy as mine is?

 

[Deano1234]

Re: Jet 45 on a 16' harbercraft

Hey thanks for the info, where do you buy shims for these, any marine stores I go into around here give me a blank look when I tell them I have an outboard with a jet on it. As far as noise goes, I didn't think it was that loud. It sounded like an outboard motor to me when we were in it, but when I asked people on the beach they said they could hear me go across the lake. I don't really care though, I still think its a pretty cool set-up.

Deano

 

[longshanks]

Re: Jet 45 on a 16' harbercraft

Mine is a real howler, and same as you describe: louder on shore than it is in the boat. The jet pump intake on mine sits about 2" above the back of the hull, at the top of a tunnel, and due to the fact that exhaust comes out over the water, it is loud.

You shouldn't need new shims, there are typically 8 or 9 of them on the main drive shaft. By moving the shims from the bottom to the top of the impeller, you bring the impeller down, closer to the sleeve, and the resulting tighter clearance gives you more power. Just make sure that there is enough clearance there to slide a paper between the impeller and the sleeve. I think that article explains it fairly clearly.

good luck