Converting Yamaha 150 V-Max 2-Stroke Propeller Drive to Jet Drive

I don't think you'll be happy. How would your boat run with a 100HP prop drive motor?

I am guessing the advantage you are looking for is shallow water running.

What does the Coast Guard Rating Plate on the hull say about horsepower? Is the anticipated 112 HP at least 75% of the recommended HP?

Is it impractical to trade your prop motor in and acquire a pumpjet? Can you get a rental pumpjet motor and try it out?

The boat is currently set up for lake and ocean running and I would like to run the rivers. The Coast Guard Rating Plate on the hull of my boat says Maximum prop = 150 hp and Maximum jet = 200hp, this is the max hp of the powerhead. I only want to change the drive so that I can still have the option of returning to propeller at any time. I am located in rural northern BC, Canada, and do not have an option to rent or borrow an outboard jet drive. To purchase a new 200 hp jet engine is $20,000+ and the drive conversion is only $3000, and I can't return it if it doesn't work. Is there a calculation out there to figure out if this conversion would work?

Okay, I'm with ya.

The Rating Plate says 200 HP Jet. If I remember correctly, when you use a motor less than 75% of the Rating, performance will be poor. So at 112 HP, this is less than the suggested minimum 150 HP (75% of 200). I agree with lyn, short on power.

It sounds like you are looking for some formula for this solution. This is all I have for you. We do have some pretty good boat guys here at CR4, let's hope somebody comes along with a more complete answer.

Best of luck to you.

I was a boater back in the stone age ('62 CC 28' mahogany double plank hull) so unfortunately not much help from here on your potential jet conversion but interested none the less.

I did a few Google searches and came up with some pages for you.

Here is one

Here is another

These are Google "Pages" so you may have to page back a bit to get anything useful.

Note that the suffix of my searches are "Complaints" and "Reviews". I always come out of these searches better informed when researching products or techniques that are unfamiliar to me.

Hope these are of some use. Always willing to (try to) help a fellow boater.

If you do end up purchasing the conversion please check back with us and let us know how it worked out, I know I would be interested!

Good Luck

The conversion will reduce performance about 25 to 35%. All depends on the shape of the hull. What you give up in performance you gain in access to these rivers. That's the choice you need to decide. Have friends and family that have made these conversions. Brother in law even had the hull tunneled to improve that to about 15% of a loss. Even with the intake above the bottom of the boat. That keeps from shearing the jet off on the many rocks in the rivers fished.

Every hull responds differently to a jet drive. Best advice I can give is find some that has put one on that type boat.

I have fished a lot of sea runners in 18-20' range. Your jet conversion will give you the equivalent of a 115 prop. If the boat load is dispersed evenly you should be able to do 30 mph no problem. Alaska state troopers like to run 18' hewes river runners with 95 hp jets (factory jet, 115 prop) and they haul a**! As long as the foot is at the right height you should have more than enough power. I would encourage you to install a "stomp grate" on the foot.

I think this comes down to how far from where you put in that you want to be able to fish...ie: how much time you are willing to spend in transit vs fishing time...

Six degrees deadrise ain't too bad, but I'd add a couple big fat adjustable trim tabs on the stern to keep it on a plane as long and high as possible. And I'd wear a life jacket all the time running rivers up there. I spent ten years in Port Townsend, sometimes retrieving boats who met rocks...

30+ mph in rivers? What happens when you find another boat coming the other way? What about the wash on the banks? What about rocks and mudbanks?

Asha,

Mercrury make a jet lower unit for some of their OBs

I guess that making one of these fit your motor may become a bit of a mission.

You could always sell your OB and get one of (from me)

Added advantage is that it's a diesel, and is fitted via a "j" clip bar and two bolts to most any hull and is entirely self contained ( apart from fuel and battery)

and is rated 200hp. Exactly right for your hull.

Cheers,

Stu.