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Old 21 April 2004, 12:34   #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, 14:00   #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, 14:41   #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, 14:46   #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
regards tim
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Old 21 April 2004, 15:49   #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, 15:57   #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, 01:49   #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, 11:39   #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, 07:49   #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, 08:42   #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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Old 13 October 2004, 13:10   #11
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Oh s**t!

Just as I thought I understood all (well most!!) of the issues about my new boat - which I hope to collect Monday - more of that in a moment - along comes another variable to bite me in the b*m!

I have no idea what size propellor I have. I know it is a laser II, but I had sort of naively assumed there was a size which was a function of the engine as came as part of the deal. This is married to an opti 150 in a 6.5m Solent.

Do I need to worry - almost certainly not. Am I curious as to what other props might do - yes a bit. What are the issues about props? Can I have a beginner tutorial please? or pointers to an 'educational' site.

Certainly the rig I have seems to go wonderfully based on that one sea trial.

So what has gone wrong with Farfetched? Nothing, all is sorted. However....

...on Monday at 5.55pm outside a nice country pub just north of Loughborough, with me sipping a half pint of apple juice (yes, really - I had a supper planned later) and reading the lowrance manuals (sad g*t!) "bang", car alarm, hollywood squeal of brakes.....

Some gentlemen have broken the big side window of my three month old 807 and nicked my briefcase including my laptop. Most recent backup - 3 September. Not a disaster, but it has thrown the last 48 hours into a mess.

If anyone is expecting a reply to a recent email, please let me know!

Since the 807 was the tow vehicle, I have yet to collect Far Fethched from the Solent hanger. Probably Monday now......

Frustratedly,

Bruce
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Old 13 October 2004, 13:16   #12
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Bruce, really sorry to hear about your misfortune. Some people have no respect for others and their property, unfortunately for the rest of us!

For a basic guide to propellers have a look here

Looking forward to seeing you and Farfetched soon!

P.S. According to Melvyn Bragg's 'The Adventure of English', Shakespeare was the first writer to use the term 'farfetched'.
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Old 13 October 2004, 13:20   #13
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Quote:
Originally Posted by brucehawsker
However....

...on Monday at 5.55pm outside a nice country pub just north of Loughborough, with me sipping a half pint of apple juice (yes, really - I had a supper planned later) and reading the lowrance manuals (sad g*t!) "bang", car alarm, hollywood squeal of brakes.....

Some gentlemen have broken the big side window of my three month old 807 and nicked my briefcase including my laptop. Most recent backup - 3 September. Not a disaster, but it has thrown the last 48 hours into a mess.

Frustratedly,

Bruce
Bruce, as a gentleman yourself, you should know better that "gentlemen" just don't smash car side windows and nick things.

anyway sorry to hear of your troubles but WHY LEAVE YOUR BRIEFCASE AND LAPTOP VISABLE FOR SUCH OPPORTUNITY

Andre
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Old 13 October 2004, 13:21   #14
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Bruce,Sorry to hear about this,if you want to pick her up on saturday/possibly sunday or next tuesday,I can bring my tow car along.Give me a call if you need help.
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Old 13 October 2004, 13:24   #15
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Really bad news Bruce, so sorry.


Us
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Old 13 October 2004, 14:34   #16
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Reply (especially to Andre's very sensible comments):

There is nowhere to hide a briefcase in a people carrier. Ours has tinted windows, and the brief case was squeezed between front seats to make it harder to steal. All other seats were folded or left at home as I had just delivered some kit to a client.

Police said that since I had parked in nearest slot to pub door, it was 6pm, I had tinted windows, and my briefcase was as discrete as possible, there really was nothing else I could do. In their view, there was a greater risk of it getting nicked from beside my seat in the pub than from a burglar alarmed car outside. And putting a blanket over it was a sign I had something to hide...

It was a three yearold laptop, fully insured, and all the cables, dongles, software will get replaced. But it costs two+ days of time, and my abiity to work and travel is impaired until the insurers get round to delivering the new laptop

Short of padlocking it to my writst....

Incidentally, some quite valuable stuff in plastic carrier bags was not touched. Perhaps Tesco's bags rather than Antler leather computer case is the answer!

Thanks for commiserations. Only two really crucial spreadsheets have gone - almost everything was emailed to somone or backed up.

Thank you for offers of help. I should have my car before the weekend. I probably will end up launhing her on Monday or Tuesday depending on the weather. My other half will be back at work, and I would appreciate help then as it will just be my 15 year old and I.....
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Old 13 October 2004, 18:16   #17
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Bruce, some more reading for you, while you count down the hrs till you're on the water. I would have a good guess that your prop is a 21" Laser2. That seems to be the standard fit size on Optimax 150s.

Everything you wanted to know about props:
http://www.mercurymarine.com/everyth...ut_propellers5

The Mercury range of props:
http://www.mercurymarine.com/props
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Old 13 October 2004, 18:20   #18
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I have a 19" S/S laser 2 spare if anyone is interested which would look good on an Opti.

Pete
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Old 14 October 2004, 09:43   #19
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If anyone does run a 19" on a 150 Opti can you please post the results. Ours wont rev over 5250 at all with a 21" but I suspect this is as high as it will rev anyway, even if it does say different on the website... Just interested to know for sure.
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Old 14 October 2004, 10:32   #20
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Justwin, Tohatsu 6.5m rib, opti 150 with 19" S/S laser revs to 6000 at 55 mph. This is with the boat empty.

Stu's Scorpion 6.5 is 50 mph plus with Opti 150 and 19" prop too. He did try a 21 but acceleration was poor.

Pete
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