What props do you have on a Gulfstream with twin Yamaha 115's

divedoc70

New Member
Joined
Sep 26, 2020
Messages
3
Reaction score
0
Points
1
Age
50
Model
Gulfstream
OK, I already know that everyone feels that a 232 with twin 115's is under powered. That said, that is what I have and I am not buying new motors. I have a 1991 232 with Yamaha F115's. Current props are Mercury Vengeance 13.5 X 18's and I m getting 5800 rpm at around 33 kts. Can anyone with a twin 115 set up share their numbers?

Thanks to all who respond
 

PNW_Drifter

Well-Known Member
Joined
Oct 20, 2019
Messages
300
Reaction score
111
Points
43
Location
Seattle, Washington USA
Model
Seafarer
What are your goals? You didn't post how much weight your running with those numbers but sounds like you are propped pretty well considering. And that speed is great. My friend had a 91 Gulfstream that came with twin 130 2 strokes original. It could only do 25mph on his tired motors. No idea the prop.

Generally they say for a rule of thumb. Prop the boat when you're running lighter than you normally would you can easily hit redline. Then when you're running "normally loaded" with fuel and people you will be within the motor's recommended tolerances. Basically if you can't hit max RPM solo w/ light fuel, you're over propped.

A set of 4 blade props will help you out of the hole and plane at a lower speed but that performance is pretty good now.

One more idea for you, I saw a boat setup like that on Boat Trader, you could email the owner and ask him what he got. I think it's kinda rare to have that setup. But it could be worse, i've seen that boat with a F225! My boat is only a 1' shorter but 1000 lb lighter w/ the F225 and it's great but GS are heavy!
 

divedoc70

New Member
Joined
Sep 26, 2020
Messages
3
Reaction score
0
Points
1
Age
50
Model
Gulfstream
Thanks for the reply. You bring up good points about weight. I do a lot of diving and usually have 4 divers with gear onboard. Right now I have 4 blade 13 X17s on and with full fuel and no divers I can get to 32 KTS. Fully loaded I am getting around 26ish . Engines are spinning up to 6000 rpm with no weight onbaord and 58 loaded. So far I am pretty happy with the performance and don't find the boat to be a dog with 115's at all. Just wondering what others are getting.
 

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
6,360
Reaction score
644
Points
113
Location
NYC
If you don't feel like the boat is a dog and you are satisfied with top end speeds, why look for new props? The fact that your WOT loaded is lower than the unloaded tells me that you probably don't have excessive slip.
Just enjoy and spend your money of new dive gear
 

PNW_Drifter

Well-Known Member
Joined
Oct 20, 2019
Messages
300
Reaction score
111
Points
43
Location
Seattle, Washington USA
Model
Seafarer
If you don't feel like the boat is a dog and you are satisfied with top end speeds, why look for new props? The fact that your WOT loaded is lower than the unloaded tells me that you probably don't have excessive slip.
Just enjoy and spend your money of new dive gear

Agreed, sounds like you are propped as good as you're going to get. Good move on the 4 blade over the 3 with the heavy loads. About fuel, Do you have the twin tanks? If so run with the big one full and the small one empty for better performance. Fuel is a massive weight if you don't need it. I find that makes a huge difference in performance.
 

divedoc70

New Member
Joined
Sep 26, 2020
Messages
3
Reaction score
0
Points
1
Age
50
Model
Gulfstream
Thanks for the replies. I am still looking for the performance numbers of people with similar setups. I do have twin fuel tanks. My forward fuel tank has been converted to a water tank and I usually run with that half full unless I am going to be out for a few days.