Quick prop question

[benbaron]

If it can be answered quickly....currently have a laser II 19p prop on, get around 35mph wot around 4600 -I think! boat is maxum 1800mx with 135hp 3 lt mercruiser.
Im thinking about getting a high five 21p prop - at moment Ive a crap hole shot and want a good one plus a lower plan speed. Use is for wakeboarding primarily...

Will a 21p be ok or too much for the engine?

Cheers
Ben

[Ed]

Others will know better, but I think changing to a high 5 and going to a 21 will slow down your 'holeshot' not make it better..

Does the engine appear to labour when you go WOT with your laser 19p? or does it seem to spin and not 'grip'?

Have you tried blocking (or not) the holes on the 19p Laser prop?

[Brit Rider]

Borrow my 20 pitch for the weekend and find our for yourself.

Should allow a slightly higher rev (maybe 4800-4900?), wont do much for top end but should get there a touch quicker and improve handling/speedholding/general hooning ability!

Check your PM's... can include with the other bits this week if you're ok to return it afterwards/repair if you drive in to a rock?!

[betty boop]

I use the same - weight Dist does a lot so get some bodies up front if you can-- makes a big dif. get the vent holes plugged - or Alt swap between the ali prop and the Laser when u want to pull a ringo etc. I alway carry the 2 and change if plans do. -- makes life a little easier

[benbaron]

Others will know better, but I think changing to a high 5 and going to a 21 will slow down your 'holeshot' not make it better..

Does the engine appear to labour when you go WOT with your laser 19p? or does it seem to spin and not 'grip'?

Have you tried blocking (or not) the holes on the 19p Laser prop?

Well thats no good then!!! Wants to be the other way then?

I cant say i notice it labours or spins really, although I have noticed it struggle to get onto a plane sometimes with only 2 in the boat and I would hesitate to say that its spinning and not gripping (although that only seemed to happen at the beginning of the session and then calmed down a bit...) Its the hole shot and lower planing speed Im primarily interested in making better though so I can lose top end without being bothered.

No not tried blocking them off, I need to buy some bungs but not got round to it.

Mike - very kind offer and pm sent.

Weight distribution shouldnt really be a problem as in playing around there were only myself and the missues in.
I dont have the ali prop, apparently the guy lost it....What is the standard pitch on the ali? if that can be compared to?

cheers
Ben

[Brit Rider]

If thee gearing on the Alpha is the std 1.81 (Some have gone to 1.61?, i believe the std prop on the boat is the 21" x 3 Blade ally or some came with 19" x 3 Blade ally.

Your revs are about right so going down pitches will allow you to redline, going up pitches may allow higher top end but will lose hole shot (So the only way you can go is to find a more efficient or lower pitched prop!)

I like the Laser II.... Good prop!

[benbaron]

ARRGHHHHH

ok Ive ordered some bungs for the prop first off.....number 2 job is get some actual readings of speed from gps and rpm...give me something to go off. Im not going to jump into this..there is a high 5 on ebay but from what pp are saying is its too much pitch..so ideally then Im looking for a 19p or a 17p high 5...if my rpm is correct etc. I cant really say ive taken too much notice you see.....

[benbaron]

Thursday looks good so will get some accurate info then and Saturday looks to be promising weather so will hopefully get out both days.....its turning into an expensive hobby this Not mentioning the days off work as well

[Centaur]

Before you do anything, you need to establish your revs at WOT. You should then select a prop that aims to be running between 4,400 and 4,800rpm at WOT.

Going up or down 2" in pitch will probably adjust your revs by 300-400rpm. However, my experience with Hi-Five propellers suggests that they run slightly higher revs than a similarly sized prop. If you are genuinely running 4,600rpm at WOT then a 19" Hi-Five will probably suit the boat and will give you far better hole shot than a Laser II. A 21" might also work, although you would need to ensure that the boat hits a minimum of 4,400rpm at WOT with a typical amount of people, gear and fuel on board. A 21" will probably hit a slightly higher top speed than a 19", whilst probably also being quicker out of the hole than your 19" Laser II. However, if you just intend to wakeboard at 20-22mph, then I would suggest that you would be better off with the 19" Hi-Five.

You are probably too far away to collect but I have both a 19" and a 21" Hi-Five if you wanted to try before you buy.

[Gazjen]

I also have a plastic variable 4 blade prop that your welcome to borrow that goes from 15" to 21" pitch it's a good prop to get an idea for pitch.

[NikTheGeek]

I would *guess* that a 21" High Five would give lower revs compared to a 19" 3-blade because of the increase in pitch and increase in blade area, but with improved hole-shot at the expense of top end. The general rule of thumb is that if you have an ally prop and are redlining at WOT, go for the next pitch up in stainless. Not sure what your WOT revs should be, but if you are already reaching them with a stainless prop, you don't want to go up in pitch. To be fair, I have never tried a High Five, but if I were to risk one in your situation, I think I'd chance a 19" rather than a 21" if your WOT revs are spot on. If pulling is your thing, they are supposed to be very good props.

Also, if you can, check your revs with a digital tach - or car multimeter to make sure your dash gauge is reading right.

My 2p

[Gazjen]

Don't you go down a pitch anyway with a high 5? say if your happy with a 21P you go to a 20P for a high 5 or have I got confused? I seem to remember reading it somewhere

[NikTheGeek]

Its sort of what I was getting at, but not put quite as succinctly You generally go up a pitch when going from an ally to a stainless, but the High Five has a higher blade area which will affect revs so I wouldn't go up in this case. Not sure I'd drop to a 17 tho, probably stick with a 19. But I've never had one so I'm only making assumptions....

[Centaur]

Just for comparision, here are some test results from a couple of my previous boats:


Monterey 180 Edge, 3.0L 135hp:

19" Aluminium 3-blade: (over-reved) 5,300rpm @ 40mph

21" Stainless Hi-Five: 4,800rpm @ 40mph


Maxum 1900 SR3, 4.3L MPI 220hp:

19" Stainless Hi-Five: (rev-limiter) 5,000rpm @ 48.5mph; 0-30mph 7.0 seconds.

19" Stainless Vensura 4-blade: 4,800rpm @ 49.2mph; 0-30mph 7.4 seconds.

20" Stainless Aerostar 3-blade: 4,850rpm @ 50.7mph; 0-30mph 5.8 seconds (2-gear prop, 14" low pitch!).

21" Stainless Hi-Five: 4,650rpm @ 49.1; 0-30mph 7.5 seconds.


As can be seen from the above, the 19" Hi-Five pulled significantly more revs than the 19" Vensura 4-blade prop and had a lower top speed. It made me think that the Hi-Five was effectively about 1" lower in pitch, although it might be that the Vensura was effectively 1" higher!

However, if you want the ultimate in acceleration and the best top speed (and you've got very deep pockets) you have to get an Aerostar .

[Ed]

However, if you want the ultimate in acceleration and the best top speed (and you've got very deep pockets) you have to get an Aerostar .

Your not kidding, I thought oh probably not that bad... And then I saw $1990USD !!!!!!!