2008 glastron GT 185 New to Me! Over reving.

[Camdelle]

So I bought this boat on Friday and used it for the first time yesterday, This is our first boat But I have been driving boats for 35 years.

Here is the issue. On Sunday I went WOT a couple times for a minute or so. It reved up to 5100 rpm and that is to much for the volvo penta 4.3GL.

I would like to re-prop the boat.

Right now I am using a 14.3 x 19p 3 blade that owner put on.

I have a 14.5 x 21p that was original to the boat.

I also have a mercruiser vensura. 48-825900 19p 4 blade SS

As I can Hit 5100 rpm(by the dashboard gauge...(how accurate is that?) and I should be around 4200-4600..... what should I be doing to get these numbers in line?

It looks like original equipment should have been a 23p???

thank you.

 

[Maclin]

In my estimation a 19 or 21 would be in the ideal range. You may want to verify the tach with a shop tach or dwell meter with the tach option. I think first I would try out the 21p you have, see how it performs for hole shot and top speed and RPM. The previous owner may have used it solely for towing and wanted the hard pull from a dead stop, and just did not go WOT with a light load, hence the 19p fit their needs.

 

[MikDee]

I would think the 21" pitch prop should be perfect for all around, and the 19" pitch 4 blade perfect for skiing, or tubing, Try them!

 

[Maclin]

What MikD said

 

[jkust]

Double check that 4600 rpm top of your range statement...thinking if it is like the mercruiser 4.3GL it is 4850 at the top. 23 pitch if that is what it came with was just for top speed numbers. That Glastron is a pretty light boat and you are going to get some decent performance out of that high torque 4.3 (though torque is generally not discussed in the marine world as it is in the auto world). I'd switch between the 4 blade 19 and the 3 blade 21 depending on my mission for the day since it takes about a minute to change props.

 

[Camdelle]

Thank you so much all.

How would I test the tach to see how close it is to legit?

My Speedo starts at 24 MPH and I just ordered a new one to match.

The 21 I will switch to right away. Should the prop nuts be torqued to a certain spec?

I lent the 4 blade ss to a buddy to try on his boat. I will get that back and keep it in boat as spare.

thank you again ev

 

[Camdelle]

Just found out that the mercruiser vensura 48-825900 19p 4 blade SS prop is for an outboard. Guy must have thrown it in just to get rid of it.

What is the best all around prop choice for this boat?

 

[MikDee]

What macklin said, and what I confirmed. You don't want to go putting a 23" pitch prop on, and lugging the motor!

 

[jk9999]

Hi Camdelle,
I have the same boat (2008 Glastron GT185) as you do but with a Mercruiser 4.3L. The boat came with a stock 14.3 x 23p 3 blade aluminum prop. I think that setup is for best WOT speed. I get around 54 mph by speedometer and it revs at around 4500-4600 rpm. That prop however doesn't have a good hole shot if you're trying to pull a skier. I have also tried a 23p 4 blade aluminum prop which has a much better hole shot but you lose a few mph off the top end (my top speed is around 48-50 mph) and it revs around 4300-4400 rpm. I also have a 23p 3 blade stainless prop thinking it might go a little faster than the aluminum but top speed is only marginally better. I haven't moved down to a 21p prop but I can see how going to 19p would cause your boat to over-rev and i would imagine that the 21p 3 blade should bring down your revs into a better range. I think the recommended top rpm for my Mercruiser is 4800 rpm. I hope this helps. Enjoy your new boat!!