Enertia Prop Test Results how does this sound ?

[Deepblue22]

Hello Forum,

The info below is from a demo Mercury Enertia 19P prop. Looking for your comment on this performance. Also a prop recommendation as this is likely not quite the right prop yet. I am using it for offshore fishing generally travelling 30+ miles distance through some decent waves (10+foot waves not uncommon) at low-plane speeds until reach the offshore island fishing grounds so I am looking for a prop that will keep the bow appropriately cutting into the waves and offer good stability and fuel economy at low and moderate speeds.

My boat is a 2002 Striper with the volvo 5.0GXi 270Hp and the SX 1.60 Outdrive. The boat is 21 foot, has the cuddy and the alaska windshield/roof. 105gal fuel. Typical day trip weight includes: boat dry weight 4034 plus 1000+lbs people, gear (and fish) plus weight of the fuel.

Test weight 4034 + 750people + 750fuel = 5500lbs approx.

4300rpm 43.0mph
4000rpm 40.0mph
3500rpm 32.6mph
3000rpm 25.9mph
2500rpm 13.7mph

Leg was trimmed fairly high up for the full rpm tests and adjusted down for the low RPM tests. Also no trim tabs for 4300 and 4000, some trim tabs down at 3500 and 3000 and max trim tabs and leg trim full down at 2500. Tests were done on a lake no wind or currents affecting. Approx 2000feet elevation.

Last detail is that the motor may be mounted too low. That diagnosis was indicated in a previous post of mine on this forum anyways. The motor seems to be splitting water into 2 roostertail streams above the anti-ventilation plate. I dont know why this boat would not be properly set up. I have a video of it if anyone would be able to comment.

Cheers and thanks in advance !

 

[hwsiii]

Re: Enertia Prop Test Results how does this sound ?

I would like to see the video.


H

 

[Deepblue22]

Re: Enertia Prop Test Results how does this sound ?

Hi Hwsiii,

This link below I hope will work. It goes to photobucket where I have uploaded a couple pics of the boat and some videos. The video called "best view" clearly shows the problem and was filmed at midrange speed.

The stern view photo shows old aluminum prop and a depth sounder transducer which I have totally removed favouring a shoot-through-hull mount inside the bilge.

http://s640.photobucket.com/albums/uu129/striper2101/

 

[Deepblue22]

Re: Enertia Prop Test Results how does this sound ?

Result of "Roostertail ?" post in this forum suggest motor is mounted too deep. Additional discussion available at:

http://forums.iboats.com/showthread.php?t=329796

At this time looking for help with selecting best prop based on previous details in this thread. Thanks in advance.

Cheers...

 

[hwsiii]

Re: Enertia Prop Test Results how does this sound ?

Can you tell me what the recommended RPM are for your motor. Because i found some information that implied it was about 5,000 RPM. And the speeds that you posted are they with GPS.



H

 

[Deepblue22]

Re: Enertia Prop Test Results how does this sound ?

The particular model is the 5.0Gxi-B(F). The operator's manual lists 4600-5000 and the volvo website for this model lists just 5000.

 

[Deepblue22]

Re: Enertia Prop Test Results how does this sound ?

The speeds were from GPS.

 

[Tail_Gunner]

Re: Enertia Prop Test Results how does this sound ?

As to the Rooster tail that is a pretty busy transom..you tabs are more than likey to be the cause..I take it you tabs are hydraulic...8" from your drive is really a bit to close another very good source of a tail and could cause a lot of turbulance in the water flow when your launching ..not good

As to the drive height it is just fine..Question on those tabs...are the flush with the bottom of the boat when there in the up postion..that is the hull and tab bottom are like on flat line no bumps aka .....................____________-----------Dark line tabs broken spaced line hull..If so not good.

Your tabs will fuction at there best in a postion somewhat like this.....

Heres a pic of another volvo drive sx notice the cav plate at the bottom of the vee same as your's

Id drop the tabs get a donor 17 pitch and see if you cant get to 4950 rpm that is the electronic rev limiter..

I just took a peak at your vids, your tabs are dragging which is not good and you are not getting to much lift with that Enertia....a Stilletto 4 blads bay pro 11 would be a great choice for that boat.But first you need to resolve those tabs...further outboard and flat with the hull and when full raised they should leave no foot print in you wake at high plane.


On the bright side your numbers are very good for a boat like that..10% slip is great. You just have to much prop for the load your doing..Ive just spent some time with a prop calc..using your numbers and playing with pitch i dont see a way to increase your speed meaning your at your hull's limit..Now it just a matter of fine tuing aka tabs and lowering the pitch a bit to prevent lugging.

http://www.go-fast.com/Prop_Slip_Calculator.htm

Play with it a bit changing pitch and with the proper rpm levels and it stays with in 1-3 mph.

 

[hwsiii]

Re: Enertia Prop Test Results how does this sound ?

Blue, in my opinion you need to be running a 17" pitch prop with the load you carry at times, and if you are going to be running at 2,000 elevation regularly. The 19" enertia only has a prop slip of 11% , even with the heavy load you are carrying, so in my opinion it is not doing bad at all. I will show you my numbers and how I got there.


Boat and Motor

Prop Picker

I will let Dhadley tell you what he recommends for the best prop for your boat and motor, as he has much more qualifications in that area than I do.


H

 

[Deepblue22]

Re: Enertia Prop Test Results how does this sound ?

Tailgunner and Hwsiii,
Great replies thanks a ton for your recommendations.

At present I have removed the trim tab plates and rotated the pistons upward. I will do a lake test soon.

On the weekend I will go back to the prop shop and see what else they have to demo. I hope to try a 4-blade if they have one.

 

[solar7647]

Re: Enertia Prop Test Results how does this sound ?

I think you need a prop change. You are moving a lot of weight with a lot of power for three blade alluminum prop. I think you are just getting way to much air in the prop. I would go up to a 4 blade prop witch will increase the bite of the prop and come down to a 17 inch pitch. The increase in bite a lone will get rid of some air, alos I think you should go to a SS prop it wont flex as I am sure the aliminum one is.

 

[Tail_Gunner]

Re: Enertia Prop Test Results how does this sound ?

Thank you that is the general ideal...