High thrust outboards

Anyone have any experience with them? I am going to repower my Nomad trawler and considering one. I presently have a 1991 Honda 45 hp that still runs but is starting to have issues(tilt/trim, oil leaks).
The one I am looking at is a Suzuki 50 hp high thrust. It spins a 14" prop vs the 11" on the standard engine and the lower unit is geared differently.
Not to much price difference but would like to hear from folks that have had experience with them.

I don't have any personal experience with them, but a bigger prop with a lower ratio makes a lot of sense for trawler use. I always put a smaller pitch prop on my outboards used on a dinghy. It let it produce more thrust to get up on plane and would handle more weight.

You won't be getting up on plane -, but the larger prop will be much more efficient than even the smaller prop with less pitch.

David

I had a hi thrust 9.9 Yamaha on my MacGregor 36 sailing catamaran. Loved it.

My experience on small sailboats with outboards up till then was to drop the engine, open the throttle, open the cooler, rummage around for the coldest beverage, pop it, take a long pull, take a leisurely look around, and about then the boat would start moving.

With the Hi Thrust Yamaha when you put it in gear you had to be holding onto something because the boat moved with authority like right now

I would not hesitate to buy another for the right application

Nimble1 said:

Anyone have any experience with them? I am going to repower my Nomad trawler and considering one. I presently have a 1991 Honda 45 hp that still runs but is starting to have issues(tilt/trim, oil leaks).
The one I am looking at is a Suzuki 50 hp high thrust. It spins a 14" prop vs the 11" on the standard engine and the lower unit is geared differently.
Not to much price difference but would like to hear from folks that have had experience with them.

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I would most certainly go with a high thrust outboard. I was planning to purchase a new Nomad several years ago and had done considerable research on the best outboard for it. I was planning to go the high thrust route (different gear ratio and prop).

What was your final decision regarding the outboard?

This thread on "High Thrust" outboard interests me. So... I went net surfing.

Utilizing same powered engine: Larger prop being geared to turn slow is what provides added thrust efficiency to move bigger [and heaver] floating items at rather slow, yet somewhat respectable speeds through water. As compared to a smaller prop geared to turn fast that churns/whisks the water providing little "bite" in the water and therefore greatly less efficiency for forward speed of bigger heavier items.

The above analogy, regarding High Thrust outboards, seems somewhat equivalent to engines/props on displacement boats... being that a big prop geared to turn at slow rpm is more "thrust" efficient than small props geared to turn quickly.

This brings me to the point of gear ratios and prop size in regard to planing hulls. In this case... it incorporates elevated instances of hull-to-water friction and hull actuated water mass movement and how "on top" of the water the boat hull bottom can get... creating less hull to water contact. Thus, less friction via less water movement and reduced water contact by the hull establishes opportunity for smaller props turning at higher speeds to become more efficient as the general means of "screwing through the water", and, much less apt to churn/whisk the contacted water.

Yea Boats!!!

Happy "Boat/Water-Movement" Daze! - Art -

Vashon_Trawler said:

What was your final decision regarding the outboard?

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I went with the Suzuki 50hp High Thrust and couldn't be happier. The extra thrust is amazing and the larger lower unit really helps with the way the boat tracks. It was a good decision.

Nimble1, do you also notice increased thrust in reverse?

CaptDon01 said:

Nimble1, do you also notice increased thrust in reverse?

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A Hi Thrust Outboard is still an outboard. With my 9.9 Yamahas they still have thru hub exhaust so the prop is eating exhaust in reverse. I'm sure its more thrust than a conventional outboard because of the larger prop diameter, but in my experience it's typical outboard in reverse performance, meaning: put it in reverse, throttle up, see lots of bubbling and hear lots of noise, eventually boat starts to move in reverse.

I had a 9.9 Yamaha high-thrust outboard on my 22' Catalina sailboat. That motor was such a joy that I dumped sailing and went over to trawlers.

Nimble1,
I chose the 60hp Suzuki (older - the first S 4-stroke) as it had the lowest gear ratio and biggest prop clearence. All other things being equal (in this regard they are pretty close) that’s about all there is to thrust.

The reason I asked was because we had the 6 HP Tohatsu Sail-Pro, (which comes with a high thrust prop), on our wing keeled Catalina-22 MK-II. There was a HUGE difference in reverse thrust. I notice minimal thrust with the 50 HP Honda on our new to us Nomad.

Nimble Nomad,
Proeller design changes reverse thrust considerably. Props that are symmetrical or/and have no cup or are the same pitch throughout the blade are better at reverse thrust. Also lightly loaded and perhaps high aspect ratio helps too. Blades that look a bit like ping pong paddles would probably be good.

Just some thoughts.

Nimble Nomads are usually over powered and if so frequently a prop poor at fwd thrust will be good in reverse.

Thanks, yes, the blades do look like ping-pong paddles

Don

Also, a boat hull is designed to go forward. It is considerably harder to move a hull backwards so the gearing is going to be different.

MP Propeller

The prop on my Willard is constant pitch and w symetrical blades.

Fishing boats and other commercial boats like that older design prop for it's good reverse thrust. I decided it would be good on the Willard as I have a little excess power. Don't need maximum efficiency in fwd gear. 2-5% less is not an issue.

I also think it may be good at shedding various lines (fishing 3 strand ect) and weed like kelp. Don't remember who said that though. The shape of the blades go w the curvy lines of the hull .. for whatever that's worth. Thought it may be smoother but I don't really know about that either. The whole system is quite smooth to very smooth.

Don't use the grey cold galvanize anymore.

Benthic2 said:

Also, a boat hull is designed to go forward. It is considerably harder to move a hull backwards so the gearing is going to be different.

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Not the case w FD hulls.

Benthic2 said:

Also, a boat hull is designed to go forward. It is considerably harder to move a hull backwards so the gearing is going to be different.

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Yup planing hulls and many SD hulls w flat transoms are like bull dozers in reverse. But FD hulls back similar to going fwd. Usually the biggest difference on a FD boat is the lower efficiency of most props in reverse. And if one gets up 3 knots or more tremendous forces can be put on the rudder. SD hulls usually have smaller rudders and steering backwards is very iffy.
The edit function goes to sleep way to fast on this forum. That’s why these two posts seem too much the same.

I spent a lot of time on a Pearson 26 with a 9.9 Johnson. The motor was great in forward.....was just a noise maker in reverse. It had a massive rudder, but was barely controllable in reverse. I always attributed it to the design of the hull to be super efficient in forward, with no regard to reverse.

Benthic2 said:

I spent a lot of time on a Pearson 26 with a 9.9 Johnson. The motor was great in forward.....was just a noise maker in reverse. It had a massive rudder, but was barely controllable in reverse. I always attributed it to the design of the hull to be super efficient in forward, with no regard to reverse.

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Only laterally related, but here's a 'standard' prop I had for my old Evinrude 9.9 that I used on a 23 ft trailer sailor (it's actually a MW prop, but looks the same), and the Mickey Mouse-eared high-thrust prop Evinrude also sold for them. The so-called high-thrust did have more oomph than the stock item, and marginally more in reverse. The original I believe was a 10x8 or 9" pitch, and the high-thrust is a 10x7", but with sort-of big ears.

Maybe someday I'll have another Evinrude/Johnson 9.9 or 15 to use them on.

Sorry for the late reply to this thread but had to put lots of things on hold due to 5 1/2 weeks of chemo and radiation. I WILL be boating next week...LOL
As far as reverse thrust, being an old sailboater, I always approach docks slowly and with the old Honda, usually it took a lot of throttle to make a difference.
I can say that the Suzuki does have substantially more reverse thrust. In fact I have had to modify my throttle application to start with idle and barely add more if needed. It does stop better.