Thank you Brian - GW204!!!

gwwannabe

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My local Suzi dealer raised my motors today. He said they were mounted where they're supposed to be IF mounted on the transom. As you said, they were mounted too low. Had to wait until 7 PM tonight for high tide so I could launch it and try it out.

What an incredible difference in performance! At 4,200 rpm, I was doing 27.5 mph, 1 mph faster than before at wot, 6200 rpm. At 5,000 rpm it was doing 33 and at wot, I hit 39+ mph. All these speeds are into the wind. I also found I could bring the Bennett trim tabs all the way up and just trim with the motor.

I still have the problem of falling off plane when my speed drops to 25 or lower. I've done a lot of reading in the forums and it seems like the Gulfstream may need to be moving about 25 or better to get up on plane and stay there. How about it Gulfstream owners - about what speed does your stern start to settle?

I have Powertek 13 1/4 x 18 4 blade props on there now but they performed exactly like the 3 bladed 14 x 18s did except they came out of the hole quicker. I got no additional lift out of them either. I'm going to swap them for a set with more pitch, at least 19s if not 20s. I'm also having my 3 bladed props cupped so they'll be like 14 x 19s and keep them for spares.

Again, thank you Brian for mentioning this. I was coming out of my skin over the weekend in anticipation even tho' I tried very hard not to let my expectations get out of hand. The results were way better than I'd hoped for. I haven't stopped grinning for the last 2 hours!

Gary 93 Gulfstream
 
I'm going to jump in and suggest you increase diameter instead of pitch.

We went from the usual Yamaha Black SS 13.75x17" to PowerTech 15.25x16". Lost just a little top end, but significant improvement all across the range, and can hold the boat up on plane at 16-17kts.

Brian
 
ocnslr said:
I'm going to jump in and suggest you increase diameter instead of pitch.

We went from the usual Yamaha Black SS 13.75x17" to PowerTech 15.25x16". Lost just a little top end, but significant improvement all across the range, and can hold the boat up on plane at 16-17kts.

Brian

I will have to agree with that also.
 
I agree with both of you on the larger diameter but no one makes a 4 blade SS prop for my motor in a 14 inch or larger diameter. That's not quite accurate - I can't get the counter-rotating prop for the pair. I don't think I can fit more than a 14 1/4 under the cav plate. I never dreamed getting props would be this difficult and I started with Bay Propeller.

Brian, thanks for the info on your planing speed - I was going to PM you to ask.

Gary 93 Gulfstream
 
Yep, you need more diameter. Look into Merc Mirage Plus wheels. I put them (15-1/4 x 19) on my old Sailfish and if I remember correctly could hold plan right around 20 mph.

Glad to hear your moving in the right direction. It's amazing how much different a boat can be when it's set up properly. :)
 
gwwannabe said:
I agree with both of you on the larger diameter but no one makes a 4 blade SS prop for my motor in a 14 inch or larger diameter. Gary 93 Gulfstream

What engines do you have on there?

I thought of the 175 Suzi when we repowered in Nov' 2005, but they weren't available so we went with the Yamaha F150s.
 
Brian, I have a pair of Suzi DF140's. For those not familiar with the Suzis, they're the 140 HP four stroke motors. These, like the DF150s and 175s are in-line 4 cylinder motors.

Gary 93 Gulfstream