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  #131  
Old 07-10-2009
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by boat has been out of the water for the last two years so nothing to report. However I am working on it now to get it back in the water in the next couple weeks. I am taking it down to Charleston on my honeymoon for a week or so and will have lots of data by the time I'm done with that.

The guys at www.internetouboards.com have given me a 5.99 pitch high thrust prop to see what kind of impact that has on performance.
I can't say enough good things about Elvin and the guys at Internetoutboards.com they didn't even sell me the engine and have done more to help me than the dealer that sold me the outboard or tohatsu USA did.

So when I get back here mid august I will post a full report on how the high thrust prop does.


I did put the motor on a 7ft dingy about a year ago with the 6 pitch prop and though it did a little better rpm wise it still didn't reach it rated rpm even up on plane. I will say this after sitting a year and half or so with no use it cranked on the second pull and ran with no issues whatsoever.

One of the other owners of my model boat put a 9.8 ultra longshaft tohatsu on their boat and it pushed it to 6.5 knots at half throttle and 7 at wot. There comment was that it ran smoother and quieter being a 2 cylindar vs the 6 and unders 1 cylindar.
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  #132  
Old 07-10-2009
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I'd point out that the little 6HP tohatsu is not designed as a sailboat auxiliary outboard, and as such does not necessarily have a prop designed for that purpose available to it.
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  #133  
Old 07-10-2009
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Quote:
Originally Posted by sailingdog View Post
I'd point out that the little 6HP tohatsu is not designed as a sailboat auxiliary outboard, and as such does not necessarily have a prop designed for that purpose available to it.
Point well taken. And if I were starting from zero, I would buy a H/T motor designed from the ground up. But at this point, I'm thinking I may be able to have something that'll work for now without much additional expense. I wasn't aware that any prop was available for these little motors except a small bladed high speed prop designed for planing boats. Been there/done that with a 6hp Evinrude on a Catalina 22. I always thought the HP was enough if I could just get that HP transferred to the water. Which I couldn't with the props that were available back then.

But the prop I'm seeing now, with the wider blades, is at least an improvement for a heavy load application. How much of an improvement remains to be seen. But for $100 bucks, as opposed to a couple thousand for a true H/T motor design, I think I may at least give it a riffle. I was hoping Audeojude had already tried it and maybe could save me even the $100 LoL!

And Audeojude, congrats on the nuptials!! :-)
I haven't found one yet that loves to polish stainless and fiberglass, much less can cook in cramped quarters at a 45 degree angle ;-)
I'm still lookin' though ;-)

Rick
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  #134  
Old 07-11-2009
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Lightbulb

HT (high-thrust) props, especially for the small motors, are a recent thing. Many are available from only from Solas. In fact, the HT props for the Tohatsu, and the other flavors of the Tohatsu (Nissan, Merc) 8/9.8 are in fact remarketed Solas Amita-4 4-blade HT props. We sell them as part of our "sail" configuration. My personal 7,000+ pound sailboat is equipped with a 9.8 (the 15 would not fit in the lazarette, or that would be the aux of choice) and gets adequate speed performance with the 5-pitch HT prop... That and absolutely stellar slow speed control.

Compare that with my old 2-smoke, points-and-condenser '74 'rude 15, and the 'rude lost by every measure. And there wasn't any Solas HT 4-blade prop for the 'rude until very recently. In cruising dress, at 8,000 pounds, the Tohatsu 9.8 beats the 'rude 15 in all categories -- noise, economy, smoke, weight, reliability -- but top speed is a wee bit (roughly half a knot) lower.

One thing I can personally verify is that subtle changes in prop pitch have a HUGE effect when pushing a heavy sailboat with a small motor. The 7-pitch HT prop will limit my 9.8 to 4,800 RPM at WOT, while the 5-pitch HT prop allows the motor to go all the way to 6,000. This effect will be exacerbated with the smaller 1-cylinder models. If you want a full 6 hp from the 6, it really does need the correct propping to allow it to reach correct WOT RPM.

The 3-blade HT "merc" prop for the 4/5/6 Tohatsu works well. But again, the 4/5/6 is primarily a 1-cylinder dinghy motor, and was not designed to push a 4,000-pound (with crew and gear) displacement hull. There is a 6 hp configuration with 25" UL shaft, which I have rigged on 2,000-to-3,000-pound sailboats (with the EE "elephant ear" 3-blade "merc" prop), which works OK. I would still opt for the (much smoother) 2-cylinder 8/9.8 if the budget and boat can handle the weight (82 pounds).

To clarify, the difference in the Tohatsu 4/5/6 is the carburetor, not just jets. And yes, the 6 hp carb does give you 50% more, government-measured, prop hp, compared with the 4 hp carb. FWIW, the most-overlooked power loss item on the 4/5/6 is not adjusting the valves after break-in. Makes a big difference in top end. The "hot setup" in the 4/5/6 family is to buy the 4, with the onboard fuel tank (which the 5/6 does not have), and then upgrade the carb to a 6 version. Then you have the option of reserving fuel to get you home when you forget to fill up. Happens more often than you'd think, because the 6 uses only about 1/2 gph at WOT.

Just don't expect the little 6 to push a barge to planing speeds.
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  #135  
Old 07-11-2009
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Well.... according to the specs, my boat weighs 2500 lbs. It feels more like 3200-3500 when I'm towing it behind my Jeep though. I'm going to weigh it on a log truck scale soon so I'll know for sure. But that, of course, will mean a second trip to the scale with only the trailer so to find out what the boat boat weighs by itself. We shall see. But I think it's going to be a close call as to whether or not 6hp will be enough, even with the H/T prop.
And now that I'm looking, I'm not finding a shaft extension kit for my engine. I had thought they'd be readily available. And with no prospects of finding a 25" shaft, I may not even bother with the H/T prop experiment.
Rick <---not giving up yet, still looking.

Quote:
Originally Posted by pvanv1 View Post
HT (high-thrust) props, especially for the small motors, are a recent thing. Many are available from only from Solas. In fact, the HT props for the Tohatsu, and the other flavors of the Tohatsu (Nissan, Merc) 8/9.8 are in fact remarketed Solas Amita-4 4-blade HT props. We sell them as part of our "sail" configuration. My personal 7,000+ pound sailboat is equipped with a 9.8 (the 15 would not fit in the lazarette, or that would be the aux of choice) and gets adequate speed performance with the 5-pitch HT prop... That and absolutely stellar slow speed control.

Compare that with my old 2-smoke, points-and-condenser '74 'rude 15, and the 'rude lost by every measure. And there wasn't any Solas HT 4-blade prop for the 'rude until very recently. In cruising dress, at 8,000 pounds, the Tohatsu 9.8 beats the 'rude 15 in all categories -- noise, economy, smoke, weight, reliability -- but top speed is a wee bit (roughly half a knot) lower.

One thing I can personally verify is that subtle changes in prop pitch have a HUGE effect when pushing a heavy sailboat with a small motor. The 7-pitch HT prop will limit my 9.8 to 4,800 RPM at WOT, while the 5-pitch HT prop allows the motor to go all the way to 6,000. This effect will be exacerbated with the smaller 1-cylinder models. If you want a full 6 hp from the 6, it really does need the correct propping to allow it to reach correct WOT RPM.

The 3-blade HT "merc" prop for the 4/5/6 Tohatsu works well. But again, the 4/5/6 is primarily a 1-cylinder dinghy motor, and was not designed to push a 4,000-pound (with crew and gear) displacement hull. There is a 6 hp configuration with 25" UL shaft, which I have rigged on 2,000-to-3,000-pound sailboats (with the EE "elephant ear" 3-blade "merc" prop), which works OK. I would still opt for the (much smoother) 2-cylinder 8/9.8 if the budget and boat can handle the weight (82 pounds).

To clarify, the difference in the Tohatsu 4/5/6 is the carburetor, not just jets. And yes, the 6 hp carb does give you 50% more, government-measured, prop hp, compared with the 4 hp carb. FWIW, the most-overlooked power loss item on the 4/5/6 is not adjusting the valves after break-in. Makes a big difference in top end. The "hot setup" in the 4/5/6 family is to buy the 4, with the onboard fuel tank (which the 5/6 does not have), and then upgrade the carb to a 6 version. Then you have the option of reserving fuel to get you home when you forget to fill up. Happens more often than you'd think, because the 6 uses only about 1/2 gph at WOT.

Just don't expect the little 6 to push a barge to planing speeds.
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  #136  
Old 07-12-2009
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Lightbulb

"And now that I'm looking, I'm not finding a shaft extension kit for my engine. I had thought they'd be readily available. And with no prospects of finding a 25" shaft, I may not even bother with the H/T prop experiment.
Rick <---not giving up yet, still looking."

The 6 will be marginal on your vessel. You will want the EE prop, which will help a LOT. The 8/9.8 with 7-pitch HT prop would be brilliant.

The UL version of the 6 is relatively new (came out last year), so upgrade bits may be in short supply. You can call or email the factory to ask, though. Check the Tohatsu website for contact info. FWIW, It's much more cost effective to get a motor with the correct shaft length, rather than ordering the (expensive) housing extension, shift rod, water pipe, and driveshaft that you need to convert.
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  #137  
Old 07-12-2009
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Quote:
Originally Posted by sailingdog View Post
I'd point out that the little 6HP tohatsu is not designed as a sailboat auxiliary outboard, and as such does not necessarily have a prop designed for that purpose available to it.
I understand about my boat being big and heavy..

The engine didn't perform to spec rpm wise on a 8 ft dingy while up on plane with a 6 pitch prop. So on a 100 lb boat with 200 lbs of cargo including me (300 lbs total) it still didn't come within a 1000 rpm of max rpm. It did do a good job of pushing the dingy around just not to the manufactures rating.
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  #138  
Old 07-12-2009
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Quote:
Originally Posted by Phantman View Post
And Audeojude, congrats on the nuptials!! :-)
I haven't found one yet that loves to polish stainless and fiberglass, much less can cook in cramped quarters at a 45 degree angle ;-)
I'm still lookin' though ;-)
Rick
Thanks, I lucked out.. she is a gem. When I'm working on the boat she wants to know what she can do and if she can buy something for the boat... actually it's already her boat according to her

I looked up the solas blades and it's hard to tell but maybe the 5 pitch 4 blade would fit on the engine... the one that the guys at internetoutboards.com gave me is marked Y6 on the outside of the hub and has 3 blades that are each almost circular. It looks to have a bit more surface area to each blade than the stock 6 ptich I have had on there. I'm very excited to try this out. Right now I'm waiting on connector parts for my fuel line to gas tank so I can run the engine. The old fuel tank and fuel line bounced out of a friends dingy in its davit on their boat on the ocean a month or so ago and was lost. (Talk about heart failure when pricing new tanks and fuel lines.)
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  #139  
Old 07-13-2009
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Soulds like Elvin's crew issued you a "merc" prop. That's the Tohatsu HT or EE (elephant ear) prop for the 4/5/6. Likely the best setup for the 6 hp.

A big 4-blade is probably too much water for the 6 to "shovel", and while it may fit on and work -- sort of -- it would likely limit WOT a lot. You can call Solas in Tampa, and they can verify that for you, just to be sure.
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  #140  
Old 07-13-2009
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Extension kits can be found at the link below:

InternetOutboards.com - Tohatsu & Nissan Longshaft Conversion Kits
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