Prop options for a Glastron ssv 175

[NDwrench]

I have a 17" Glastron with a 4.3 mercruiser. Running a 19p and she runs well but I think the top end pushing the RPM's. (not exactly sure because the Tac is not working properly)
The boat planes very easy with a few people in it and tops out right at 50. I am considering trying a 21p ( aluminum) and am curious if that will cause problems pulling a tube or a skier?

For those of you with similar boats what has your experience been.

 

[alldodge]

More pitch does not mean more speed, in fact most cases there is less speed. The more pitch the more HP needed. You need to be able to reach max WOT RPM. If you cannot get the rpms, then you must drop pitch or the engine will be damaged over time from lugging.

To find out how your doing you have to have an accurate tach
Need GPS speed (a gps, phone app, fish finder, etc)
Need to know what your drive ratio is
Need engine serial number or at least year and if its EFI or MPI

 

[NDwrench]

The 1995 4.3 has a recommended WOT rpm of 4500 -4800, final drive is 1.84:1 according to the book. This is the carburated version that I believe is around 180HP. I wold have to go back and look at the exact model numbers for the engine and drive.

I have to mess with the instrument panel and see why the tachometer is not working. It sticks sometimes.

 

[jimmbo]

4400 - 4800 is the WOT range

If the tach is sticking, replace it, as it really can't be trusted

 

[alldodge]

The year and carb is enough info to determine max WOT as jimmbo listed

WOT 4400 -4800
Drive ratio 1:84
Prop 19 Pitch
Speed 50 (boat speed-o and not accurate)

If all the above rpm and sped was accurate your slip would be
4400 rpm -16 % negative number is an error
4800 rpm -6 % also error

My guess is your probably doing around 40 to 45 mph.

Can get a hand held tach which is more accurate in most cases then the boat tach. Not to say many of the boat tachs are very accurate

Get us some good speed and rpm numbers and we can work the problem

 

[jimmbo]

As less than Accurate a Water Pressure Speedometer can be, GPS speed readings need careful interpretation too. GPS measures Ground Speed only. If there is any current in the body of water, a GPS speed reading will be inaccurate in regards to Water speed.

 

[QBhoy]

Hi. If your hull is anything like the 167 ssv I just sold...you don’t want to go much more than 50 to be honest. The 167 turned on a hell of a bad chine walk at 52/53 gps. Dangerous and no sign of settling down after it at all. 50 would do just fine haha.

 

[QBhoy]

Of course many influences can cause what I’ve said above. Perhaps yours would be different.

 

[Scott06]

Get a shop tach or dash tach working before you play with props, current WOT is key for decision making or props. Going up in pitch would generally be trouble for any water sports towing in my experince.

 

[porscheguy]

I ran a 19p aluminum on my 19’ wellcraft last year that has a 4.3lx and a 1.84 ratio. I think I hit maybe 42/43mph and was clearly on the rev limiter with the throttle at 80% or 90%. My boat originally came with a 1990 spec 4.3 (165hp) and it had a 21p aluminum prop when I got it.

What I’m saying here is my boat is a bit bigger than yours, a bit heavier, and now has a bit more power. If I can use high performance stainless props in a 21p with good results on mine, you’ll probably be fine to use a 21p aluminum on yours. It probably won’t do as well towing as it would with the 19p, but many of us change props depending on what we’re doing that day.

 

[NDwrench]

I ran a 19p aluminum on my 19’ wellcraft last year that has a 4.3lx and a 1.84 ratio. I think I hit maybe 42/43mph and was clearly on the rev limiter with the throttle at 80% or 90%. My boat originally came with a 1990 spec 4.3 (165hp) and it had a 21p aluminum prop when I got it.

What I’m saying here is my boat is a bit bigger than yours, a bit heavier, and now has a bit more power. If I can use high performance stainless props in a 21p with good results on mine, you’ll probably be fine to use a 21p aluminum on yours. It probably won’t do as well towing as it would with the 19p, but many of us change props depending on what we’re doing that day.

This was sort of my thinking. A fairly light boat/small hull with a decent engine. We were tubing this weekend and it does that effortlessly, both my Brother and I ski so we will see how that goes. I think the previous owner did a lot of wake boarding and maybe wanted to keep the boat pushing off plane. I am working on the electrical gremlins in my instrument panel to get the tach working.