23'

[dknesich]

I have a 23' with twin 115 yammi 4strokes. Was wondering if anyone else had the same set up and if so, what they were turning @ WOT and cruise. I'm topping out @ 5600 RPM wich is about 31knots. I feel like I should be higher. I also have trouble plaining at reduced speeds. I bot the boat used so I don't know what props are on there.

[McGillicuddy]

Greetings dknesich, and welcome aboard.

I dont have the same set-up but I think that's about as good as its gonna get with those motors. That's over 800 lbs for 230 hp and the drag of 2 lowers. Your RPMs are where they should be, but I think due to gear ratio differences the small props of the Yammies have less blade area than say the Suzuki 115s and cannot offer as much locomotion, er, propulsion. I'd get the biggest diameter props that motor can handle and reduce the pitch to stay in your desired RPM range.

But realistically, 36 mph or so ain't bad. If those motors aren't on a flotation bracket that probably hurts a bit. I presume you have trim tabs. If not, getting some big ones would be my first recommendation. That will certainly help lower your planing speed. With that power to weight I would be surprised if you can stay on plane at 20 mph.

I also doubt you can plane using only one motor.

I think that hull favors more power. If those Yammies are pretty new I'd be tempted to sell em and look for single good 250 HPDI or the like with the proceeds.

Good luck and enjoy your new ride.

[BigLew]

For what it's worth, I have an '85 Scepter with a 260 Volvo I/O and want to go to 300-350 I/O. It is nice, but just doesn't seem to be as nimble as it should be when up on plane and running a bit over cruise. Yes, I do have tabs but probably a bit on the small side.

Good luck.

[ScottM]

Contact "Briguy" on this site. He's had that setup on his 23 CC for several years and appears to love it.

[Abe's Rocket]

I think a 300hp outboard would be the perfect motor

[Bushwacker]

I think Brian has twin Zukes on his rig, which have more gear reduction and swing bigger props, so not quite the same as twin Yammi's.

[ReelToy]

I have a 23 cc and it's knocking on the door of 50mph with a 250 2 stroke Yamaha,bracket and mercury mirage 17 inch prop. A little tweaking and your boat should be quicker. Try different props and height of motors on transom. Though your motors will never plane that fast, that is just the way 4 strokes are. But you get allot better economy.

[Gary Hill]

That sounds like a old friend's SEACRAFT with a full transom and from VA Beach, VA. He did that since had a 225 before and figured this would be a good set-up.

[dknesich]

Thx, how do i adjust the height of the motors? and how do i tell what pitch my props are? Like I said. I bought the boat used so don't have that info.

[ScottM]

Height is adjusted with the mounting bolts. Keep the trim tab on the engines within 1" of the keel for optimum performance. Prop size should be stamped on the outside of the hub with either their diameter & pitch (respectively) or a model # that can be cross-referenced through the mfg.