DF300 23 Sceptre

[Fr. Frank]

I think you're still a little low, based upon your running photos. You've got serious spray ABOVE the spray deflector, so your cavitation plate which is below that will certainly have water pressure above it. That water pressure above the plate pulls the motor downward, creating significantly more hull drag. It's like having the opposite of a stern-lifting prop.

The advice you're getting here is good: raise the motor first. Then worry about a jack plate, if necessary, and only then try to fly the right prop.

[Briguy]

You don't have prop issues. You have height issues. Bring that badd ass bitch over to my yacht club next weekend. We'll use the 4000# sailboat lift and Jack your motor up 2 holes.
That should give you 200-300 rpms.

When I first installed my twin 115's they were too low. 5600 rpms. 2 bolt holes up got them to 5950.

Also, are you trimming that motor until she blowed out??? We're you running WOT into a 3 knot tide??? Wind????

[gofastsandman]

Originally Posted by Briguy

You don't have prop issues. You have height issues. Bring that badd ass bitch over to my yacht club next weekend. We'll use the 4000# sailboat lift and Jack your motor up 2 holes.
That should give you 200-300 rpms.

When I first installed my twin 115's they were too low. 5600 rpms. 2 bolt holes up got them to 5950.

Also, are you trimming that motor until she blowed out??? We're you running WOT into a 3 knot tide??? Wind???? Did you have fat chicks on board????

Jenna`s gonna smack yo azz.

[Briguy]

Haha. Just kidding!!!!

2 bolt holes will do the trick. Adding some tabs and getting rid of the wedges
will help also. Changing motor height can be done in 1/2 hour or less with proper
tools and a tube of 4200.

My only real question is we don't know Danny's true hull weight. 50 mph should
be doable.

[Snookerd]

Picked up 200 rpms and 3 mph today- got her up to 47 mph. Less weight, maybe loosened up, and better fuel cycling through the tank. Motor will get raised soon....

[Snookerd]

Saturday on the Manatee River....

[kmoose]

Originally Posted by Snookerd

Picked up 200 rpms and 3 mph today- got her up to 47 mph. Less weight, maybe loosened up, and better fuel cycling through the tank. Motor will get raised soon....

What prop are you using now and what is you WOT rpm? Looks like your right at 41 knots.

I got lot's of different numbers based on tide direction and wind. It's so hard to find a clean place to run without variables that affect what your trying to find a baseline for. The lowest fuel burn at an average cruising speed is going to be the best indicator for propping. Top speed is a dragon everyone seems to chase but in reality the best mpg with an average loading is what needs to be nailed down.

[Snookerd]

Finally ran the boat after the 20hr service and raised the motor all the way on the transom. Hit 6K RPM's for the 1st time with the 18.5 prop. I was at 48 mph at 6K with 3 people and 1/2 a tank. My slippage is only 6% according to Mercury's calculator. Looks like I'm dialed as much I am going to get dialed! Put about 65 miles on her yesterday.

Jonas had a good time handling her for half the trip. Personal auto pilot!

[gofastsandman]

Originally Posted by Snookerd

Finally ran the boat after the 20hr service and raised the motor all the way on the transom. Hit 6K RPM's for the 1st time with the 18.5 prop. I was at 48 mph at 6K with 3 people and 1/2 a tank. My slippage is only 6% according to Mercury's calculator. Looks like I'm dialed as much I am going to get dialed! Put about 65 miles on her yesterday.

Jonas had a good time handling her for half the trip. Personal auto pilot!

That sounds great Danny.
She will loosen up with more hours.
6% is a strong number.

[Snookerd]

Thanks Sandy. I am so pleased with it! I have to say, being jacked that high with low slippage, those new lower units do NOT need to run low like the 1st gen lowers. I know offshore you run slower, but running close to 50 to get out to Tampa Bay and back to the ramp sure feels good.