Mercury 150hp optimax 2006 revs

[newman7]

My engine is pulling 4,600rpm flat out. I'm sure it's meant to be in the 5,800 range?
I have a laserII (believe 21p) and have been told it's the correct prop - surely I need something different?

Thanks in advance

[Zander]

Originally Posted by newman7

My engine is pulling 4,600rpm flat out. I'm sure it's meant to be in the 5,800 range?
I have a laserII (believe 21p) and have been told it's the correct prop - surely I need something different?

Thanks in advance

Lower the Pitch? When you are testing, how much is the engine trimmed out? How high up is the engine? Mabyw you dont get the boat "up" correctly?

[newman7]

That's 4,6 with it trimmed out fully.
I believe the engine could be moved a little higher but does cavitation a little already.
Do you have a suggestion on what actual prop to try though?

[sinkunit0]

Sounds a bit sick should certainly be pulling more than that . I've only got experience of 200hp merc .but the min I ever ran was a 23 pitch and that easy did 6400. Check the filters and obvious stuff then get your cheque book out and head down to your local marine mechanic.

[sinkunit0]

What speed are you getting 60 mph?gps check the setting on your tachometer if it's some where near that.

[newman7]

53mph gps
Pretty sure it's not sick as it had a full check over by race marine 6 hours previously and also had a check over by ribs marine 2 weeks ago as well while it needed a new fuel filter to be fitted so pretty sure it's running properly!

[Zander]

Many of my friends here in Sweden that have Phantoms use Tempest or Rakers quite a lot. 53 miles aint much to be honest. But then again the water in UK is quite alot more rough than the waters in Sweden...

[newman7]

Hmm maybe I'll try one of these props you've suggested. I know 53 isn't much but if I can get it to pull high 5s then it should definitely increase and be about the correct speed for a phantom. I'll look into the tempest and raker thanks. (53 was set in fairly okay waters)

[russ williams]

Your 150 hp optimax should be giving full rev range with a 21 pitch prop , sounds like your engine is running to deep as the lazer is a semi surface prop ,do you think the hight setup of your engine is to low

If not then there is most certainly something wrong with the power output of the engine

[newman7]

Yeah I think you're right - I'm going to raise it up the transom. An old friend who has always raced boats just had a look at it and first glance said the engine is probably too low.

[Paul E]

Have you got any pictures of your set up?

[newman7]

These are the only images I have as I'm away, not sure if they can help?

[newman7]

Here's the other

[Zander]

Just to be sure, you dont have the trimtank full or the pads down right?
(Dont take this the wrong way, just wonna make sure )

[newman7]

We've shut the bow tank off completely and tabs are adjusted while going, nothing to do with either

[grandmas denture]

... your box is 1.87:1, to get 55mph, 5800 rpms with laser 21 at 15% slip are needed

... engine height isnt that low, check your rev counter