Laser II - Right prop?

[Alan Vaughan]

Folks, I am running a 21" Laser II on a 2000 135 HP Mercury behind a 17 ft fibreglass cabin boat. It shows 61 mph at 6100 rpm. I am seldom up there but am starting to wonder if I need to go even higher in pitch. If I do 'standing starts' in gear and just take off at full throttle I have to have the trim already out a bit as I get to say 55 mph so quick that I actually beat the trim if I started trimmed right in. Also, as these 2000 series 135s gave so much trouble being leaned down too much I have been leaving the 3 bungs out of the prop - I get the equivalent of wheel spin sometimes going from 4000 to 5000 or 5 to 6000 rpm. The boat catches up OK but I have just put them back in but haven't tried them out yet. I had removed them to aid the stalling I was getting originally when going through 2000 rpm. That appears to be OK now so maybe the bungs need to be back - will test on 3rd Jan. Any thoughts on the prop appreciated. Its just that most pitches I see are 18s or 19s. Cheers, AV, New Zealand.

 

[walleyehed]

Re: Laser II - Right prop?

Either your tach, or speedo is wrong....6100RPM with 21" prop showing 61MPH is 5% NEGATIVE slip.....I'm just guessing here, but I think your speedo is off.<br />2:1 gear ratio at 6100 w/21" prop, best case would be 55MPH. Might be a good idea to have the tach checked as well to be safe, don't know what tach you've got.

 

[Alan Vaughan]

Re: Laser II - Right prop?

Thanks for suggestions. I certainly will check the tacho and the speedometer. They are Mercury issue which came with the motor. I wonder if there is a way of running a 'good' tach in parallel with the Merc tach?<br /><br />Anyway, apart from running alongside someone else to check the speed, I have left it a bit late to check the tach this year. <br /><br />I will speak with the agents to see if they have a test system.<br /><br />In New Zealand we had a terrible time with this 2000 series 135HP range. Had to hold the choke in to get past 2000 rpm. Jets had to be drilled out in the end. I am surprised I cannot find other references to this model on the web.<br /><br />Thanks again. <br /><br />AV

 

[walleyehed]

Re: Laser II - Right prop?

If you can get your hands on what they call a "tiny-tach" you can compare. It's a small little unit with a sensor lead you simply wrap around the sparkplug wire. I wouldn't worry about the speedo, as the tach reading is the one that tells us what amount of work is actually being done. The speedo can be used for fine-tuning later.<br />You say choke....is that a carburated engine then???? It's a choke and not a primer valve???<br />Non-fuel injected is what I'm getting at.<br />www.tinytach.com/tinytach.html

 

[Alan Vaughan]

Re: Laser II - Right prop?

Agree re the speedo - I am only really interested in optimising my propeller pitch. I want the top revs to be close to say 5600 rpm. I will look for a tach - I guess it clips on to a spark lead like the timing light I used to use.<br /><br />Choke! Its the 12,000 miles between us. We call priming the engine with the key pushed in on the hand control 'choking' but I guess it is the same as 'priming'. I had to push the key in to get through 2000 rpm. The engine would stall otherwise. It would always start but would also stall at 2000 rpm unless the key was held in and the handle pushed through to higher revs. Went fine after that but was dangeous coming into a warf or beach. I have had Johnsons, Yamahas before but a couple of things have been interesting with the 135. Firstly the torque feels very straight line. I mean this engine just goes for it in any rev range and doesn't seem to peak much. The other thing is it seems to cool down very quickly. I will stop for an hour or two on a lake and when i go to start it needs plenty of ch..primer with the key. I squeeze the bulb every time to firm but the motor does seem to cool own. Maybe I am dreaming and thats just the way it is. It appears Mercury tried a bit too hard to lean these machines down and we all had problems. Wish I had spent more and got an injected model but I was tempted by the NZ$12,000 (US$5,500) in Nov 1999. Thanks for the chat. About to tow it all up to Lake Taupo our biggest lake on 2/1/04.<br />The boat is a small one by your standards and is the Buccaneer 525 Escape shown on this web page.<br /><br /> http://www.buccaneer.co.nz <br /><br />Cheers<br /><br />AV