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Old 05-01-2009, 11:01   #46
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While we're talking about the 9.9HP. Let me show my ignorance about the prop ring. I don't have the plastic fairings installed with my props. I was given one in a kit of spare parts but haven't tried it yet. What benefit should I see with it? Will this reduce cavitation?.

So by this statement I am to understand you are having cavitation problem? What size shafts you have on your engines?
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Old 05-01-2009, 11:28   #47
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Not sure these are the older (1999) T9.9W model. Yes I do cavitate occasionally, usually on the port side which also has a broken plate on it (thanks to the hold down latch issue) I can get about 6-6.5 knots on flat with both throttles about 2/3rds; then it starts to bite more air and less water.
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Old 05-01-2009, 11:32   #48
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All outboards have issues on cats if they are mounted near the rear of the boat. How can they not? Guys who cruise in flat, sheltered waters are less prone to complain about it. Blue water cruising brings about the desire for inboards as the outboards are constantly popping out of the water in even small waves (battery charging is another issue).

There are a few guys on this forum who have the problem and have mentioned it. I see it around here on various boats, but mostly in winter with the Northerlies. On the other hand if the outboards are mounted amidships, this will certainly solve the problem, but I would imagine that maneuverability in marinas or to fuel docks would be somewhat interesting.

Pat, yer right. Sail drives are not outboards Me bad. Yet the previous owner had fitted them. I guess they made very nice impromptu sea anchors.
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Old 05-01-2009, 12:55   #49
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Some Schionning boats can employ outboards fitted on vertical slides in wells. This puts the props in the same position as saildrives. Should eliminate prop ventilation, but it does introduce other problems - ventilating the engine bays is more involved, usually needing blowers and apparently engine corrosion happens much faster. It also means you can't have a walk through cockpit/transom set up.
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Old 05-01-2009, 13:13   #50
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If the outboards are mounted as PDQ are, retractible from the forward part of the cockpit, then they are probably 1/3 of the hull length forward of the transom. The have enough distance seperating them to also allow the boat to handle marinas, bridges, etc extremely well. With my PDQ while waiting for bridges I could literally pick a place in the water and stay spot on it while others were circling behind me. I found no issues with their location, especially after I found out that eye bolts could be threaded into the top flywheel and used in combination with the mainsheet to directly lift the engine straight up from the engine well.
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Old 05-01-2009, 14:37   #51
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Originally Posted by Pat Ross View Post
I'd like to know more about the nozzels and thrusters please post a few links you personally liked best about these products.

Thanks,

Pat
Pat you'll find a lot at www.solarnavigator.net/kort nozzle.htm
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Old 05-01-2009, 15:47   #52
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Pat you'll find a lot at www.solarnavigator.net/kort nozzle.htm
I had trouble with that link but I Googled it and got this one

KORT NOZZLES There is a underline between kort_nozzle.htm

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Old 06-01-2009, 09:08   #53
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I had trouble with that link but I Googled it and got this one

KORT NOZZLES There is a underline between kort_nozzle.htm

Pat
Pat, thank you for the correction.
It may be of interest for all to kow that I started the discussion on Power Thrusters (which led to the Kort & Rice Speed Nozzles) following receipt of advertising mailed to me by Garhauer Marine Hardware. I do not know if they work as advertised with regards to fuel savings and increased thrust (and they should to some extent), but I am confident that they a considerably reduce cavitation. They have the advantage to be cheap at $89.00. I looked at their web site and it is not shown , so here is a scan of their ad.
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Old 06-01-2009, 10:42   #54
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Garhauser

Thank you. I appreciate the information. I read all the material on the "Solar" website and took the link to the manufacturer of the Rice Nozzle and emailed them. If I get anything worth reporting I'll share it.

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Old 10-01-2009, 13:24   #55
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It just occurred to me that my outboards are further forward and deeper than quite a few saildrives I've looked at. Lucky me! I just wish somebody would come take this 5KW generator so I could get a smaller and lighter one. I haven't used my AC in three years.
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Old 15-01-2009, 06:25   #56
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Power Thruster

I have recieved no feedback from the designers and manufactures of Rice Nozzles. It appears their applications are strictly large industrial vessels.

I have had the good fortune of speaking with the designer of the Power Thruster, Burt Heidenreich Berthhc42@msn.com , an engineer , Garhauer referred me to him when I contacted them. He has designed 3 specific models including one for a dingy engine. Interesting person to speak with. He put me in contact with someone using them on his multihull sailboats who reports:

"I have used this with both catamarans and tri’s. Doesn’t matter what design. In both cases it has significantly reduced cavitation problems relating to wave action when the prop comes close to the surface creating a vortex and thus air bubble around the prop. It is always a balance of how low to set the outboard relative to the hull and most multihulls experience cavitation problems in rough water. Normal cav plates don’t work and the full tube type overload the engine when using a high thrust prop"

For the price, $89 US each, I will probably give them a shot when the time comes.

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Old 15-01-2009, 07:10   #57
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I used a similar hydrofoil stabiliser to these by doel-fin fitted to the cavitation plate

They significantly decrease cavitation, and also reduce hobby-horseing when motoring

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Old 15-01-2009, 09:53   #58
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On my 32ft Eclipse I made my own version of the fins that Talbot used for the same reasons. I made mine from scrap grp (about 8mm thick so pretty strong and much stronger than bought ones). I bolted them to the bottom leg plate as above.

They did the job when motoring, but when sailing fast (12-14 knots) in big seas off Portugal I saw that they had been ripped off as when the engine was tilted up the fins became vertical brakes.

Something to think about if you sail fast offshore. Of course not a problem if you only sail slowly in flat water (but then you shouldn't get aeration problems anyway)
Hope that helps

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Old 15-01-2009, 12:39   #59
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I rebuilt the back end of my catalac so that the fins and propellor recessed up under cover.

And the catalac didnt have the same problem of going that fast either!
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Old 16-01-2009, 18:21   #60
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I started my cruising life with a great Honda 35 outboard on my Gemini, I had very few issues with the motor popping out of the water, for some reason I may have just had great balance or just a good two years of weather. Recently I was preparing for a crossing from Isla Mujeres back to Key west, hours prior to my departure my motor gave away with very little warning.
I was lucky enough to find a 40 Honda brand new. I placed the outboard on my boat, put my original prop on and went out for a few hours to break the motor in.
What I had not expected was that the motor had to be just slightly shorter than the previous motor or the extra weight screwed up my boats performance as well as the the ability to keep the stick in the water.
I used double the fuel on my crossing, I could not get the boat near to speeds at the same throttle the previous motor functioned at, as well did I mention half way across the gulf I calculated I was using exactly double the fuel I had ever used... Thank you for my sails and not needing to get anywhere quick a three day crossing took me six.
The boat's max speed is now only six kn and I use 2 gals per hour no matter what speed I travel... One day I will screw with it more to figure out where I went wrong.

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6 crossings and counting!
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