What makes a power trim spacific to one engine & would trim help on a jet drive?

udoittwo

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Jan 23, 2014
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73
Hello,
Sorry, but I tent to ramble, so be prepared.
New here but I have a few questions about my brother-in-law's boat. He has an 2005 50HP Suzuki jet drive on his 18' jon boat. It doesn't have power tilt/trim. We had it on a large body of water and for the most part, it worked fine. If it got a little to choppy or he opens it up on smooth water, it would cavitate[I guess that'what it's called?] and not get enough water to drive it well. He wants to toss this real nice low hours motor for something with a prop. I think there's something he can do to improve performance without buying a new motor or spending a lot of money.
1. Would power trim, like it does on a prop boat, help at accelerate and get better preformance at high end on a jet drive?
2. I see relatively inexpensive used power trim units but wrong HP or make. Can any trim unit be adapted to any motor?
3. The drive is only a few inches below the bottom of the boat. Its not a monster motor. Does someone make, or is it easy to make, some way of quickly lowering and raising the motor to get the jet lower into the water and would that help to lower it a few inches?
Oh well, that's enough for now, I'll post a question about my motor some other time.
Thanks for your time and any help and HAVE A GREAT WEEKEND!,
Karl.
 

alldodge

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Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

:welcome: to iboats

Hello,
Sorry, but I tent to ramble, so be prepared.
New here but I have a few questions about my brother-in-law's boat. He has an 2005 50HP Suzuki jet drive on his 18' jon boat. It doesn't have power tilt/trim. We had it on a large body of water and for the most part, it worked fine. If it got a little to choppy or he opens it up on smooth water, it would cavitate[I guess that'what it's called?] and not get enough water to drive it well. He wants to toss this real nice low hours motor for something with a prop. I think there's something he can do to improve performance without buying a new motor or spending a lot of money.
1. Would power trim, like it does on a prop boat, help at accelerate and get better preformance at high end on a jet drive?

Power trim on a jet drive does very little on PWC and it does work, it would do next to nothing on your setup
2. I see relatively inexpensive used power trim units but wrong HP or make. Can any trim unit be adapted to any motor?

Anything is possible with time, design and money, but practicality would loose in my opinion.

3. The drive is only a few inches below the bottom of the boat. Its not a monster motor. Does someone make, or is it easy to make, some way of quickly lowering and raising the motor to get the jet lower into the water and would that help to lower it a few inches?
Oh well, that's enough for now, I'll post a question about my motor some other time.
Thanks for your time and any help and HAVE A GREAT WEEKEND!,
Karl.

Lowering the intake grate is the way to go, if feasible, or change the intake grate fins to reach further into the water. Keep in mind if the jet of water is not pushing against water and only air no increase would be found. Maybe a combination of changing the initial angle of the jet along with the intake grate.
 

Frank Acampora

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Joined
Jan 19, 2007
Messages
12,004
Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

Lowering the whole engine will actually decrease performance if the pump unit is in the water--way more drag. If the jet exhausts into the water, again thrust will be lost, The jet must exhaust into free air. The only thing you can do is to be certain the pick-up is always in solid water--and there is the main problem with jet drives. In rough water they lose suction and thrust due to air ingestion. Why do you think there are NO jet drive ocean racers?

Jet drives are specifically made to exhaust parallel to the hull bottom. A power trim unit would be counter-productive.

Your BIL may very well be correct. Small jet drive outboards are mostly used in rocky rivers for fishing. At any rate, if he is disgruntled and wants a prop drive, --- You know the saying---Whatever floats your boat. His boat, his decision.
 

ondarvr

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Apr 6, 2005
Messages
11,527
Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

Re: What makes a power trim spacific to one engine & would trim help on a jet drive?

1. Yes it will help, not to the degree it would with a prop, but it can make a difference. I adjust mine differently depending on the situation or conditions. Rougher water may need a slightly lower position to not ventilate, on smooth water adjusting the trim can gain or lose a couple MPH with very little change in angle.

2. Yes you can buy after market T&T kits that will work, might be pricy to get the right one.

3. The Jon boat probably has ribs on the bottom, these tend to trap air and funnel it right to the pump in rough water. Lowering the motor (I don't mean tilting this time) can help in eliminating the problem, but it may also slow the boat down, they are very sensitive on height, even 1/4 can make a difference. Jon boats normally need the pump mounted lower. You can raise and lower it by unbolting it, lowering it and putting the bolts back in.

Every hull will be different and you can't always get it perfect for every condition, raising the motor may help top speed, lowering it may slow it down but eliminate the ventilation, you just need to find what works best for you.

The best option is to change it over to a prop if it's not going to be used in shallow water, there will be a huge boost in performance and mileage.
 
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