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Author Topic:   MONTAUK 170: HighFive Propeller for 90-HP

Georgetech posted 12-24-2004 03:40 PM ET (US)
Would a Mercury HighFive propeller be suitable for use on a 170-MONTAUK with a 90-HP Mercury two-stroke?
Clark Roberts posted 12-25-2004 10:22 AM ET (US)
George (yellow jacket?) a HighFive is notable for its traction and smoothness. One with the proper pitch (allows engine to run at wide open throttle ...wot... at top of recommended rpm range) will give you a good solid hole shot and very smooth performance all the way up... turbine smooth! I ran a 20-inch pitch HighFive on a 1979 Newport with 1995-96 Merc 90 and it was a perfect combination with rocket starts and top speed right at 50-MPH at 5600-RPM. I noticed no performance penalty over a 20-inch pitch three-blade Trophy; in fact, it handled better (maybe just my imagination), could be trimmed out higher and for sure held tighter in sharp turns. The HighFive is a great prop in my opinion. Happy Whalin'... Clark... Spruce Creek Navy
Georgetech posted 12-25-2004 07:28 PM ET (US)
Hi,Clark
Thanks for the information. I will order mine in the size 12 3/4 x 20 to replace the aluminum three blade which is 12 3/4 x 21 on my 170 Montauk with 90hp Mercury saltwater series 2 cycle engine.
Clark Roberts posted 12-26-2004 07:37 AM ET (US)
George, your 170 weighs a bit more than my Newport but I think that 90 Mercury will swing a 20" at near 5500. You might try fine tuning the engine mounting height to make sure it's high enough (anti cavitation plate about 1 1/2 - 2" above keel should be about right) and install a Doel-Fin. Let us know how she goes and happy Whalin'... Clark... Spruce Creek Navy
jimh posted 12-26-2004 09:41 AM ET (US)
Let us know how the HighFive performs, particularly its effect on the engine's wide-open-throttle (WOT) speed.
By changing to a stainless steel five-blade 20-inch pitch propeller from an aluminum three-blade 21-inch pitch propeller of the same diameter, I would expect you will see some drop in engine WOT speed. I am curious how much.
Georgetech posted 12-26-2004 04:23 PM ET (US)
Clark and Jimh
I live in New Jersey so I will have to wait until spring to test it. I do not want to make a mistake so in the meanwhile I wrote to Boston Whaler asking their opinion about what size should I be using with either the High Five or LaserII. I do understand that a stainless steel propeller has a better bite than the aluminum one, so I thought keeping the same diameter but decreasing the pitch by one inch will end more or less within the 5000 to 5500 rpms maybe I'm wrong. Let me wait for their response. I thinking of protecting this propeller by installing one of the new guards available nowdays.
OutrageMan posted 12-26-2004 05:49 PM ET (US)
I did not go with the 5 blade, but when I went from a factory 3 blade to a revolution 4, I had to drop 2". You are adding a lot of mass and weight with the stainless, then add to that the addition of the extra blades, and you have to make up for it with a lower pitch.
Brian
imko posted 12-28-2004 03:59 PM ET (US)
I have a Montauk 170 whit differend props installed.
(mercury 90 4-stroke 2003, max rpm=6000)
The first was a Vengeance 13,25 x 18 => 6200 rpm, and hit 42 Mph (rpm to high !!!)The mid range 3000-4000Rpm is
not good.
The second was a Trophy Plus (4 blade) 13,75 x 19
5400 RPM and hit 43 Mph. The engine was not running smooth
whit this prop. Mid range was oke, but WOT the boat was very difficult to handel. (to much bow lift when engine
trimmed up.)
Mercury told me that i better could use a 3 blade prop
whit this problem.
The third prop is a Laser II 13,25 x 20. => 5700 Rpm and hit 44,1 Mph. The engine is running smooth comparing the
4 blade Trophy Plus!! For overall performance and top speed
go for the Laser!!!!

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Author	Topic: MONTAUK 170: HighFive Propeller for 90-HP
Georgetech	posted 12-24-2004 03:40 PM ET (US) Would a Mercury HighFive propeller be suitable for use on a 170-MONTAUK with a 90-HP Mercury two-stroke?
Clark Roberts	posted 12-25-2004 10:22 AM ET (US) George (yellow jacket?) a HighFive is notable for its traction and smoothness. One with the proper pitch (allows engine to run at wide open throttle ...wot... at top of recommended rpm range) will give you a good solid hole shot and very smooth performance all the way up... turbine smooth! I ran a 20-inch pitch HighFive on a 1979 Newport with 1995-96 Merc 90 and it was a perfect combination with rocket starts and top speed right at 50-MPH at 5600-RPM. I noticed no performance penalty over a 20-inch pitch three-blade Trophy; in fact, it handled better (maybe just my imagination), could be trimmed out higher and for sure held tighter in sharp turns. The HighFive is a great prop in my opinion. Happy Whalin'... Clark... Spruce Creek Navy
Georgetech	posted 12-25-2004 07:28 PM ET (US) Hi,Clark Thanks for the information. I will order mine in the size 12 3/4 x 20 to replace the aluminum three blade which is 12 3/4 x 21 on my 170 Montauk with 90hp Mercury saltwater series 2 cycle engine.
Clark Roberts	posted 12-26-2004 07:37 AM ET (US) George, your 170 weighs a bit more than my Newport but I think that 90 Mercury will swing a 20" at near 5500. You might try fine tuning the engine mounting height to make sure it's high enough (anti cavitation plate about 1 1/2 - 2" above keel should be about right) and install a Doel-Fin. Let us know how she goes and happy Whalin'... Clark... Spruce Creek Navy
jimh	posted 12-26-2004 09:41 AM ET (US) Let us know how the HighFive performs, particularly its effect on the engine's wide-open-throttle (WOT) speed. By changing to a stainless steel five-blade 20-inch pitch propeller from an aluminum three-blade 21-inch pitch propeller of the same diameter, I would expect you will see some drop in engine WOT speed. I am curious how much.
Georgetech	posted 12-26-2004 04:23 PM ET (US) Clark and Jimh I live in New Jersey so I will have to wait until spring to test it. I do not want to make a mistake so in the meanwhile I wrote to Boston Whaler asking their opinion about what size should I be using with either the High Five or LaserII. I do understand that a stainless steel propeller has a better bite than the aluminum one, so I thought keeping the same diameter but decreasing the pitch by one inch will end more or less within the 5000 to 5500 rpms maybe I'm wrong. Let me wait for their response. I thinking of protecting this propeller by installing one of the new guards available nowdays.
OutrageMan	posted 12-26-2004 05:49 PM ET (US) I did not go with the 5 blade, but when I went from a factory 3 blade to a revolution 4, I had to drop 2". You are adding a lot of mass and weight with the stainless, then add to that the addition of the extra blades, and you have to make up for it with a lower pitch. Brian
imko	posted 12-28-2004 03:59 PM ET (US) I have a Montauk 170 whit differend props installed. (mercury 90 4-stroke 2003, max rpm=6000) The first was a Vengeance 13,25 x 18 => 6200 rpm, and hit 42 Mph (rpm to high !!!)The mid range 3000-4000Rpm is not good. The second was a Trophy Plus (4 blade) 13,75 x 19 5400 RPM and hit 43 Mph. The engine was not running smooth whit this prop. Mid range was oke, but WOT the boat was very difficult to handel. (to much bow lift when engine trimmed up.) Mercury told me that i better could use a 3 blade prop whit this problem. The third prop is a Laser II 13,25 x 20. => 5700 Rpm and hit 44,1 Mph. The engine is running smooth comparing the 4 blade Trophy Plus!! For overall performance and top speed go for the Laser!!!!