High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

[ns22simple]

I have a Nonsuch 22 sailboat (+/- 4,900lb) with a 1994 Tohatsu 9.9 EPL (Longshaft/2 Stroke) with a factory #8 3 blade prop (9.2" D X 7.8"P)

I desire to upgrade to a 4 blade high thrust prop. I feel there is too much slip with the stock 3 blade prop.

My first choice is the Tohatsu 4 blade 10"DX7"P high thrust (Part#3ZOB645143)

I am also aware that Solas offers two 4 blade high thrust props for this motor:
- 10"DX7"P (Part#5113-100-07)
- 10"DX5"P (Part#5113-100-05)

My first choice would be the Tohatsu as it is designated as a "high thrust" prop for my engine by the manufactuer.

Any advice would be appreciated.

NS22 "Simple"

 

[Sea Rider]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Welcome to the forums,

Install a Tiny Tach or Hardline induction tach, go full wot with your actual set up and check max rpm achieved at wot, that way will know how much under propped to start with. That horse runs 4500-5300 rpm at wot.

You could update that 9.9 to a 15 HP for peanuts cost testing same prop to check if betwen 5200-5800 rpm at wot, depending on achieved rpm, you still have 7 & 6 standard pitch props for heavy boats uses to pick, or a 4 blade high trust prop. Anyway will need a induction tach to check wether standard or high trust props use to be inside factory rpm stated.

Happy Boating

 

[pvanv]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Simple,

As I noted on the SailNet forum, you want the Tohatsu 7" pitch prop. I speak from experience, both as a Certified Tohatsu tech, and from personal experience on my Hinterhoeller HR28. On my (heavier) rig, the 7 pitch kept the RPM too low, well below optimum speed. I run the 5 pitch, and just barely hit max WOT RPM... not enough to hit the ESG. Your Tohatsu 9.9 has about the same total torque as my 9.8, and your cat boat (yes, I am very familiar with George Hinterhoeller's boats, built a scant 15 miles from my shop), while not as heavy as my sloop, is in the range for the Tohatsu 3Z0B645143, PROPELLER (7) 4 BLADE X 10 X 7 (F15/20C), $122.58. That part is available from any Tohatsu/Nissan dealer, including me.

 

[pvanv]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Welcome to the forums,

Install a Tiny Tach or Hardline induction tach, go full wot with your actual set up and check max rpm achieved at wot, that way will know how much under propped to start with. That horse runs 4500-5300 rpm at wot.

You could update that 9.9 to a 15 HP for peanuts cost testing same prop to check if betwen 5200-5800 rpm at wot, depending on achieved rpm, you still have 7 & 6 standard pitch props for heavy boats uses to pick, or a 4 blade high trust prop. Anyway will need a induction tach to check wether standard or high trust props use as factory rpm stated.

Happy Boating

Luis,

He has a displacement hull. Your rules for planing hulls don't apply. In all fairness, the 9.9 is more than he needs. Today, we use either the 6 hp sail pro, or the 9.8 UL HT motors on boats of his kind.

 

[Sea Rider]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Paul,

Nobody said anything about planing a sailboat, all of them are non planing hulls. A friend of mine who used a Yam 9.9 with standard delivered prop on a heavy 30 footer sailboat was completely dissatisfied with it's performance, converted the engine to a 15 HP, placed a induction tach went pitch down, now engine revs 200 rpm less than max wot parameters factory stated and can trasnport 12 passengers at 5-6 knots at less than 3/4 throttle for hours on choppy seas and high winds.

Has optimized his engine performance much satisfactorily than before. In Lima most of the sail boaters 25" + uses 15-18-20 long shaft engines maily because are family oriented going full passenger capacity and need a punch engine to take them back when wind dies all of a sudden while being very far away from port. NS22 Simple is using a Tohatsu 2 strokes 9.9 that could be optimized if needing the extra power into a 15 HP for peanuts cost along a proper pitch prop to improve his boating expectations...

It's preferable having extra available power and not needing it untill the time you will desperately need it.

Happy Boating

 

[pvanv]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Yes, power in reserve is good; he may want to consider that upgrade separately. His question was whether to select a 5 or 7 pitch, which are his only HT prop options. We use the 5 on on a 9.8 4-stroke on my 8,000 pound (loaded) 28 footer, and run a 7 on 4-stroke 9.8 on a Catalina 25. Both work well. Just more pitch on the smaller boat. I have done lots of these props, and the 7 pitch is good up to about 5,000 pounds of displacement. On the heavier boats, the 7 pitch does not allow the motor to come up to correct wot rpm.

 

[TwoRivers]

Re: High Thrust Prop for Tohatsu 9.9 on Nonsuch 22

Luis,
Thanks for the picture. We just got 8 inches of snow here.