DF300 23 Sceptre

[kmoose]

Originally Posted by Snookerd

Finally got past the break in restriction to be able to go WOT. Max is 5650 rpm @ 38.5 knots. Definitely dragging arse! Tell me about those manual plates.

There is more going on than what a plate will fix but it will help. Were you able to confirm the throttle body linkage is allowing WOT?

[HeadHunter]

At 5650 engine RPM you have a prop RPM of 2716. On the Moose's boat, he would have to be turning 6219 engine RPM to match your prop RPM of 2716.

His boat will do 38.5 K around the same 5650 RPM that your boat is doing but at only 2467 prop RPM. You are spinning an identical prop roughly 10% faster to achieve the same speed with no wind catching top on your boat. Hmmnnnn..


I'd check the prop first. Just because it looks good doesn't mean it is good. Could have been re-pitched before it came to you? etc.

If the prop checks out, raise the motor a pin hole and retry. My experience with the 23 hulls show you need to be an inch higher than the deadrise point, maybe an inch and a half.

I'm not a huge fan of bolt on brackets but will admit that Kennys set up performs great. If after verifying the prop is "right" and raising the engine doesn't solve your issue, I'd def consider bolting on a 10" set back bracket.

[DonV]

I don't know Danny, the best I've ever had my boat in perfect conditions, light load and really skint back was 51 mph on the GPS. You are at 44 mph (38.5 knots) so I would think you should be able to get to the 43 knots/50 mph with a light load, perfect conditions.

The idea behind the jack plate is you can easily adjust the engine so the cavitation plate is even with the water and parallel with the water as it comes off the transom/hull's edge. Remember the water comes up from the bottom edge of the transom at around a 10 degree angle, I'm guessing on that angle, might be more, so if the cavitation plate is too low the water, the water is not hitting on just the sharpest point of the gear case causing extra drag. Look at the "streamline" design at the front of the gear case at and below the cavitation plate, now add the two to three inches above that which is also plowing through the water if it's mounted too low.....more drag. That's my theory and I'm sticking to it.

[kmoose]

Originally Posted by DonV

I don't know Danny, the best I've ever had my boat in perfect conditions, light load and really skint back was 51 mph on the GPS. You are at 44 mph (38.5 knots) so I would think you should be able to get to the 43 knots/50 mph with a light load, perfect conditions.

The idea behind the jack plate is you can easily adjust the engine so the cavitation plate is even with the water and parallel with the water as it comes off the transom/hull's edge. Remember the water comes up from the bottom edge of the transom at around a 10 degree angle, I'm guessing on that angle, might be more, so if the cavitation plate is too low the water, the water is not hitting on just the sharpest point of the gear case causing extra drag. Look at the "streamline" design at the front of the gear case at and below the cavitation plate, now add the two to three inches above that which is also plowing through the water if it's mounted too low.....more drag. That's my theory and I'm sticking to it.

That seems to be the consensus for some of us discussing it offline. As Bushwacker suggested it is best to get the motor up high enough before the prop swapping starts. I would love to see a pic of the motor down in running position and a straight edge coming of the keel. My guess is the motor is more than a few holes too low and will require a bracket like I linked to get it up where it needs to be. They even make one with half the set back of the 10' if putting it back there is of any concern. Considering my 250 is a 30" motor his is probably close to the weight of mine minus the center section weight and shouldn't care either way.

[Rufneck]

Would you recommend the jack plate on a 23' Sceptre that already has a Hermco bracket? I am already concerned about maneuverability at low speeds and so I am concerned that an additional 10" will just make it worse.

[Snookerd]

It looks to be above the keel an inch already?!

[Snookerd]

No visual of anti cav plate

[Snookerd]

Plate running

[Snookerd]

Plate

[gofastsandman]

Put the level on the bottom of the keel and extend back just far enough to see the AV plate with both parallel.

Hey Lamont come here you big dummie.
Esther, your so ugly I could stick your face in dough and make
Gorilla cookies.