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Old 21 April 2004, 13:34   #1
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Laser II Propeller sizes and compatability

Evening all,

After discovering numerous fractures in my aluminium propeller I thought that now would be a good time to obtain a stainless one. I am thinking about a Lazer II and there are several around, secondhand, but I want to be sure of sizing and compatibility before I buy.

1. Are pitch sizes in 1 inch increments - I have seen both 19" and 20" offered for sale. I was under the impression that sizes were odd and in two inch increments.

2. I have been offered a 20" pitch prop that has previously been fitted to a 90hp Honda. Does anyone know if the Honda gearcase is likely to be the same size and spline type as my 90hp Mariner.

3. My current aluminium propeller is 19" pitch and I can pull about 5500 rpm with the boat light. The recommended WOT range is 5000 to 5500rpm. Should I stick with 19" pitch or go up to 20" or even 21" - I have had conflicting advice on this.

Any thoughts most welcome.

Regards

Duncan
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Old 21 April 2004, 15:00   #2
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I could be wrong, but I'm pretty sure the Lazer 2 only comes in equal sizes, ie, 20" 22" 24" to suit your motor as
you need to use whats known as a small hub!
The odd numbers are Lge hub for 135hp+

Merc, Mariner and Honda splines are all identical, Honda used to use a merc lower unit, may still do.

If you are currently running a 19" ally, I would try a 20" Lazer. Beaulieau is a good source for props, don't pay anymore than 100.00 for a good en.

Part no for a 20" Lazer 2 small hub is: 48-16990A46
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Old 21 April 2004, 15:41   #3
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Just checked my Merc Laser II prop and it's definitely a 21P, which I'm assuming is 21". (Normally bolted on a 175hp 2 stroke). So they come in odd numbers but is that the same as a Lazer?

ATB
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Old 21 April 2004, 15:46   #4
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i have a merc 150 opti with a laser 21 changing back down to a 19 as only getting 5200
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Old 21 April 2004, 16:49   #5
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The clue is in the wording!!!

Lge hub Lazers are ODD sizes.
Sml hub Lazers are EVEN sizes.

It's not that difficult is it!!!
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Old 21 April 2004, 16:57   #6
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Interesting tim that you are going to change down... i too am only pulling 5200rpm, but @ 46knts. Accn is more than adequate so I think changing down to a 19" will just mean higher rev's, more fuel and no more top speed. I'll be very interested to hear the outcome. When i get round to it i'll try it too, but for now i'm just happy yottin about at 40+ knts

Dirk is 100% right about the ODD and EVEN thing. My Yam 130 took EVEN Laser II's (small hub) and my new 150 v6 takes ODD Laser II's (large hub).
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Old 22 April 2004, 02:49   #7
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Thanks all

Quote:
Originally Posted by Dirk Diggler
The clue is in the wording!!!

Lge hub Lazers are ODD sizes.
Sml hub Lazers are EVEN sizes.
Many thanks all.

So I guess that a 20" is what I'm after - just got to do some haggling now!

Duncan
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Old 22 April 2004, 12:39   #8
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Hi Daniel
i'm only changing down to see the difference on boat speed fuel economy
so will let you know , moved up in size because of the weght being carried for charter work i am not a mechanic so am just doing it out of interest and the need for speed (for fun) but normal cruising speed is 25/30 knots or less depending on weather and conditions and its more economical
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Old 12 October 2004, 08:49   #9
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Quote:
Originally Posted by tim griffin
Hi Daniel
i'm only changing down to see the difference on boat speed fuel economy
so will let you know
Hi Tim,

Have you got any results from your experiment yet ?

I ask because I'm running a 23" on a 150 OPTI and looking at some other threads it looks like 23" is a but much.

Cheers

Phil
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Old 12 October 2004, 09:42   #10
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Tim, I'm in the same boat too, any luck with the 19" Laser2.

Like Daniel I'm pulling 5250rpm @ 48kts running a 21" Laser2. I find that this setup gives me sh*tloads of accel'n already so I don't really need to change down to a 19", however if I could hit 50kts I might be tempted.

How much is a Laser2 19" & 21" in the UK out of curiousity?
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