df300 2015 likes being deep?

[barrell]

My 237 Cobia is now a year old and Im still not thrilled with my 16 x 3 x 18.5 Suzuki prop. I get to 5800rpms and 45 mph but Id like to get to 6,000rpms. I would like a buit more speed. Everyone thinks I should be at 50mph with a df300 on a 24 foot boat. However my boat seems a bit stern heavy. I am considering a four blade to get some lift but I would also love to test a 16x17 three blades to see the results. I know the cav plate should be skimming above the water but my df300 does not like the cav plate there. It performs better with the cav plate buried a bit. I guess my question is do all 300's like being buried a bit deep. That's what Ive read dozens of times on THT. Or is it because of me prop the motor seems to prefer to have the cav plate buried? I have a Atlas jack plate so I can put the motor wherever I want it.

[Harper]

You probably won't like my answer much....People give out their opinions real easy when it comes to what speed you "should be getting with ___ motor on ___ boat." There are so many variables, that such statements are mostly just so much porcine suds. The only suggestion that I can offer, if you're seeking a few more MPH out of your "stern heavy" setup is to spend the bucks on a hydaulic jackplate. Setting the motor back 6" or so from the stern will result in less need for trimming of the motor, helping to lift the stern a little and the jackplate can be adjusted for optimum height. The prop will also be in a little "cleaner" water column.

[barrell]

You probably won't like my answer much....People give out their opinions real easy when it comes to what speed you "should be getting with ___ motor on ___ boat." There are so many variables, that such statements are mostly just so much porcine suds. The only suggestion that I can offer, if you're seeking a few more MPH out of your "stern heavy" setup is to spend the bucks on a hydaulic jackplate. Setting the motor back 6" or so from the stern will result in less need for trimming of the motor, helping to lift the stern a little and the jackplate can be adjusted for optimum height. The prop will also be in a little "cleaner" water column.

You missed all that in my post and the picture. The motor has an atlas plate. However the dealer put a 12 inch on. Im having it removed in September and replaced as a six inch by removing the spacer. Its not just what people say, all the major motor manufacturers show 300's getting low 50's on similar (not exact) boats in their test reports. What my question was do others think their df300
run better deep?

[Harper]

Ha! You're right. I missed the last sentence. So why do you say the motor doesn't like running with the cav plate skimming the surface? in what way does it preform better slightly buried? Not that just slightly buried is going to cause enough drag to slow you down. But I'm curious. I have to go a little deeper sometimes to, but only because of sea conditions.

I understood your question....being to other DF300 owners. But still contend that any answer you get will not tell you why you aren't getting the additional 5 MPH you seek. Still too many variables to say that there is a reason. You're obviously pushing a lot of wind with your setup. So it's not just water or hull configuration that becomes a factor.

I would think your trim tabs would help with the heaviness at the stern also. Although I have no experience with trim tabs.

[ChrigelKarrer]

I have
1 DF200 (29ft Panga with tunnel hull)
1 DF300AP (29ft RIB with bracket)
1 TWIN DF300AP (34ft CC with bracket/eurotransom)
All 3 engines need to run deep and tucked in, otherwise they ventilate.

There are some things i learned while doing numerous tests:
1° Suzuki 16'' propeller work better than lesser diameter propellers
2° on all 3 boats the AV plate must be deeper than normal or below the hull
3° cruising angle can affect ventilation, try to change your weight distribution
4° any transducers, tru-hulls or other protrusion in front of the LU will lead to ventilation
5° the speed reduction of one hole lower is marginal and around a few mph's
6° trim tabs will help to avoid blow-outs when going over the hump, but add drag while cruising while using them.

I most likely will install hydraulic jack plates on the 34ft Venture CC so that i can react to different loads and sea conditions.

Chris