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Author Topic:   RITE HITE Jackplate

Teak Oil posted 04-14-2005 03:34 PM ET (US)
I installed my Rite Hite adjustable 6-inch jackplate today on my Montauk and went for a test drive. The engine is a 1985 Evinrude 90. With the engine level I am 1 3/8-inch above the keel of the boat.
As soon as I got on plane I realized I am probably too low because I was getting a "V" spray from the outdrive. I gained 2-MPH and about 500-RPM. However I also noticed the prop cavitated pretty easily on sharp turns, so if I raise the engine to about 2-inches then won't it cavitate easier?
Also I am going to need another prop. My stainless Michigan Wheel 13x19 touched 6000-RPM at about 46.5mph. If I use 5900-RPM I calculate a 13-percent slip which sounds pretty high.
So to me it sounds like a 21-inch prop like a Laser or Rapture and raising the engine to about 2-inches above the keel may be the way to go. I am just concerned about the cavitation
Any tips?
Bob

Teak Oil posted 04-14-2005 04:14 PM ET (US)
Here is a pic of when it was at 1 3/8"
http://photobucket.com/albums/v735/MontaukBob/?action=view¤t=DCP_1154.jpg
LHG posted 04-14-2005 07:37 PM ET (US)
Nice installation. You could even be too high at 1-3/8" for the elephant ear prop you are running, giving you false RPM readings. 47-MPH is just about right for a 90 on a Montauk, and assuming the engine redlines at 5500 and has a 2.0 gear ratio, the 19 pitch would be correct. I'd drop it down until the slippage goes away, then you will know if 19" pitch is still correct.
Then, if you want to raise it up, you can buy a surfacing prop of the correct pitch, such as the 19" Rapture. Mercury Laser II's are made in even nubers, 20-26". A 20 could be perfect for you if the engine can turn it. If gear ratio is lower (numerically higher) than 2.0, than more pitch could be used, 21 or 22".
kamie posted 04-14-2005 07:39 PM ET (US)
Teak Oil,
I will let the experts discuss how high you should go and the prop pitch, how easy was your jackplate to adjust? I was going to try to adjust mine up/down but I realized I have the engine tilted up and the battery off already.
Teak Oil posted 04-14-2005 10:04 PM ET (US)
Is some "V" spray normal with a jack plate installation then?
Larry I am glad you replied, I have been looking at Laser props on eBay and at Scream and Fly, and I am seeing a lot of them listed with odd pitch numbers. Are the odd pitch numbers an older version of the Laser prop? Also will any Laser with the Flo Torq hub fit my gearcase, or do I need a "small hub" gear case?
Kamie its pretty easy to adjust on the trailer. I mounted my engine one hole up to give me more clearance to get to the adjusting nut on the jack plate. Just loosen the four outside nuts and crank it up or down with the adjusting nut. I was going to adjust it on the water today but I forgot to bring my 3/8 to 1/2" adapter so I sat in the river staring at the sockets.
LHG posted 04-14-2005 10:40 PM ET (US)
Speaking of Laser II props, I just had dinner with Dave, who took a 21" Laser II off my hands for his 150. The V-6's use the odd numbered props, and the 4-1/4" (70-125HP) use even numbered pitch. That's just the way Mercury makes them.
Teak Oil posted 04-14-2005 11:04 PM ET (US)
Thanks now I get it.
Speaking of Dave, Larry you should come freeze with us this weekend in Holland. I am looking forward to meeting him and Gambler. I have made it a goal of mine to check out T/T Whale Lure and those 115's some time this summer.
Bob
JBCornwell posted 04-15-2005 08:23 AM ET (US)
I think what your prop is doing is ventilating rather than cavitating, Teak Oil.
The symptoms are the same but the mechanism is quite different and the correction is quite different.
Red aky at night. . .
JB
jimh posted 04-15-2005 08:45 AM ET (US)
[Removed dead link]
Teak Oil posted 04-15-2005 10:30 AM ET (US)
JB can you elaborate a little? You sound like Yoda, LOL
Teak Oil posted 04-15-2005 04:02 PM ET (US)
Any other tips before I buy the Laser prop?
Teak Oil posted 04-16-2005 08:27 PM ET (US)
Today I tried my OMC aluminum prop and it performed better than my stainless, at a 5/8" higher setting. I had even more V spray so I guess it is a normal occurance with a jack plate. It proves my original problem was my prop.
I think a 20" Laser will be right, since I hit 5300 rpm and 45mph with two people on today on a low setting. I have an OMC water pressure gauge on the way, which perfectly matches my original gauges. Then I can raise her higher.

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Author	Topic: RITE HITE Jackplate
Teak Oil	posted 04-14-2005 03:34 PM ET (US) I installed my Rite Hite adjustable 6-inch jackplate today on my Montauk and went for a test drive. The engine is a 1985 Evinrude 90. With the engine level I am 1 3/8-inch above the keel of the boat. As soon as I got on plane I realized I am probably too low because I was getting a "V" spray from the outdrive. I gained 2-MPH and about 500-RPM. However I also noticed the prop cavitated pretty easily on sharp turns, so if I raise the engine to about 2-inches then won't it cavitate easier? Also I am going to need another prop. My stainless Michigan Wheel 13x19 touched 6000-RPM at about 46.5mph. If I use 5900-RPM I calculate a 13-percent slip which sounds pretty high. So to me it sounds like a 21-inch prop like a Laser or Rapture and raising the engine to about 2-inches above the keel may be the way to go. I am just concerned about the cavitation Any tips? Bob
Teak Oil	posted 04-14-2005 04:14 PM ET (US) Here is a pic of when it was at 1 3/8" http://photobucket.com/albums/v735/MontaukBob/?action=view¤t=DCP_1154.jpg
LHG	posted 04-14-2005 07:37 PM ET (US) Nice installation. You could even be too high at 1-3/8" for the elephant ear prop you are running, giving you false RPM readings. 47-MPH is just about right for a 90 on a Montauk, and assuming the engine redlines at 5500 and has a 2.0 gear ratio, the 19 pitch would be correct. I'd drop it down until the slippage goes away, then you will know if 19" pitch is still correct. Then, if you want to raise it up, you can buy a surfacing prop of the correct pitch, such as the 19" Rapture. Mercury Laser II's are made in even nubers, 20-26". A 20 could be perfect for you if the engine can turn it. If gear ratio is lower (numerically higher) than 2.0, than more pitch could be used, 21 or 22".
kamie	posted 04-14-2005 07:39 PM ET (US) Teak Oil, I will let the experts discuss how high you should go and the prop pitch, how easy was your jackplate to adjust? I was going to try to adjust mine up/down but I realized I have the engine tilted up and the battery off already.
Teak Oil	posted 04-14-2005 10:04 PM ET (US) Is some "V" spray normal with a jack plate installation then? Larry I am glad you replied, I have been looking at Laser props on eBay and at Scream and Fly, and I am seeing a lot of them listed with odd pitch numbers. Are the odd pitch numbers an older version of the Laser prop? Also will any Laser with the Flo Torq hub fit my gearcase, or do I need a "small hub" gear case? Kamie its pretty easy to adjust on the trailer. I mounted my engine one hole up to give me more clearance to get to the adjusting nut on the jack plate. Just loosen the four outside nuts and crank it up or down with the adjusting nut. I was going to adjust it on the water today but I forgot to bring my 3/8 to 1/2" adapter so I sat in the river staring at the sockets.
LHG	posted 04-14-2005 10:40 PM ET (US) Speaking of Laser II props, I just had dinner with Dave, who took a 21" Laser II off my hands for his 150. The V-6's use the odd numbered props, and the 4-1/4" (70-125HP) use even numbered pitch. That's just the way Mercury makes them.
Teak Oil	posted 04-14-2005 11:04 PM ET (US) Thanks now I get it. Speaking of Dave, Larry you should come freeze with us this weekend in Holland. I am looking forward to meeting him and Gambler. I have made it a goal of mine to check out T/T Whale Lure and those 115's some time this summer. Bob
JBCornwell	posted 04-15-2005 08:23 AM ET (US) I think what your prop is doing is ventilating rather than cavitating, Teak Oil. The symptoms are the same but the mechanism is quite different and the correction is quite different. Red aky at night. . . JB
jimh	posted 04-15-2005 08:45 AM ET (US) [Removed dead link]
Teak Oil	posted 04-15-2005 10:30 AM ET (US) JB can you elaborate a little? You sound like Yoda, LOL
Teak Oil	posted 04-15-2005 04:02 PM ET (US) Any other tips before I buy the Laser prop?
Teak Oil	posted 04-16-2005 08:27 PM ET (US) Today I tried my OMC aluminum prop and it performed better than my stainless, at a 5/8" higher setting. I had even more V spray so I guess it is a normal occurance with a jack plate. It proves my original problem was my prop. I think a 20" Laser will be right, since I hit 5300 rpm and 45mph with two people on today on a low setting. I have an OMC water pressure gauge on the way, which perfectly matches my original gauges. Then I can raise her higher.