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bottomsup

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Posts: 51
Reply with quote  #1 
I have a 31Ft ocean Master with a 10ft beam.Twin 300 G2s Engines.They are mounted as high as they can go.I am using the Mercury enertia eco  16x21 I am not getting any cavitation trimmed up and props biting great all rpms.I can only get 5100 trimmed up to max before starting to cavitate.At 3550 getting 34 mph and 1.9 mph.
I am looking for best mid range speed and mpg If go to a 16x19 will I loose speed at mid range? I figure going to 19s will get me up to around 5500 to 5600.
Or if I go RX4s 15x20???? I know it is trial and error just looking for some advise
The 33 Ocean master when tested by BRP with twin 300s using 15x20s RX4s was getting 5500 RPMs wide open and at 3500 getting 33.5 mph and 2.01 mpg and the 33 is around 1000 pound heavier then I am
My boat bottom is clean and just painted

I just got 3 sets of props to try from my dealer
RX4s 15x20  
RX4s 15x18 
Mercury Mirage 14-5/8x21 3 blade
I still have the  Mercury enertia eco  16x21 3 blade

I am testing all of them this weeked
Huey

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Posts: 13,860
Reply with quote  #2 
Let's us know how she goes with these different props. Kudos to the dealer for allowing you to fine tune her.
PropNut

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Posts: 467
Reply with quote  #3 
Rebel 19 props  on the 33 Oceanmaster that was ran at Miami, it ran 52mph at 5650rpms.  I have never rode in an oceanmaster until then, really nice boats, congrats.
bottomsup

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Posts: 51
Reply with quote  #4 
I am going to try these props and go from their.I did see an Ocean Master with 300 G2s and it had the Rebel props.I have the 31 and around 1000 lbs lighter then the 33.I have around 34 inch centers on mine as well and also mounted on the stern no bracket.They are mounted as high as they can go with props spinning inward.On my old G1s I tried spinning outward and inward and found a little more stern lift with inward rotation.That is why I spun them inward on my G2s.I have my book ready with everything written down for each prop.Rpm,GPH,Mpg and speed at 3000 through 5500 so all I have to go is write in result.I did 500 Rpm differences.The weather looks good.Heading to beach to see how the ocean looks
bottomsup

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Posts: 51
Reply with quote  #5 
I tried 4 different props I had a set of Mercury Mirage plus on my old G1s 14.5/8x21 At 3500 to 3600 I used to get 33 Mph Now I am only getting 29 and the engines is 1 inch higher then my G1s. I dont have as much trim as I used to and the bow does not feel like it comes up as much.I think I need to drop the engines ???I only used to run my G1s at around 3500 to 3600.Not sure why I lost 3 mph on my old props?  My props are turning inward and I go a little better result by getting on a plane and cutting loose the tie bar.The Rpms on all the props would vary around 150 Rpm and now it only varies buy are 50 to 100. two of the props I got 1 mph faster at 3500 and 4000 Rpm.The difference is around 3/4 of an inch on the tie bar.I had them with a 1/2 of tow with the props further apart.It ended up being a around a 1/4 of tow with the props closer together I also had around 1500 pounds of weight on the boat in fuel and people                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Mercury Enertia ECO  16x21 3 blade
3000 Rpm
Mpg 1.9 Gph 13.6 Mph 27
3500
Mpg 1.8 Gph 18 Mph 32
4000
Mpg 1.5 Gph 18 Mph 37
4500
Mpg 1.3 Gph 32.8 Mph 42
Wide open
5200 Speed 49

Evinrude Rx4s 15x20 4 blade
3000 Rpm I could not get boat to stay on a plane
3500 Rpm
Mpg 1.8 Gph 17.4 Mph 32
4000 Rpm
Mpg 1.6 Gph 23.6 Mph 37
4500 
Mpg 1.3 Gph 31 Mph 41
Wide open
5300 Rpm Mph 49

Evinrude Rx4s 15x18 4 blade 
3000 Rpm
Mpg 1.9 Gph 13.3 Mph 29
3500 Rpm
Mpg 1.9 Gph 15,9 Mph 30
4000
Mpg 1.7 Gph 20.2 Mph 34
4500 Rpm
Mpg 1.5 Gph 25.1 Mph 38
Wide open 5500 Rpm 48 Mph

Mercury Mirage 14-5/8x21 3 blade 
3000 Rpm
Mpg 13.3 Gph 13.3 Mph 25
3500
Mpg 1.9 Gph 15.2 Mph 29 (With same props on G1 300s at 3500 I did32 Mph at 35 to 3600Rpm
4000
Mpg 1.7 Gph 20.7 Mph 34
4500 Rpm
Mpg 1.5 Gph 27 Mph 39
Wide open 5400 Mph 46
   

Specs from Ocean Master 33 Ft with Evinrude G2s On a bracket in stern Also it is around 1000 Lbs heavier then I am
Evinrude Rx4s 4 blade on test 
3000 Rpm Mpg 1.81 Gph 12.5 Mph 26.5
3500
Mpg 2.1 Gph 16.30 Mph 33.5
4000
Mpg 1.77 Gph 22.05 Mph 39
4500
Mpg 1.59 Gph 27.5 Mph 44
5000
Mpg 1.35 Gph 36.7 Mph 49.5
Wide open
5500
Mpg 1.13  Gph 47.5 Mph 54
 






50north

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Posts: 31
Reply with quote  #6 
so what have you decided on? I am about to go through the same exercise on a grady white 265 express. Weighs in at around 9300lbs and we have just mounted new Gen2 250ho's with 16x20 rx4 props. The dealer and tech have them mounted as low as they go and i have raised the question regarding the height but they are almost ready to bet their houses that they have it right?
We will see when we put it back in the water in a day or 2.

Dean 

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Dean
50northadventures.com
bottomsup

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Posts: 51
Reply with quote  #7 
Dean I think I have to lower my engines.I was looking at a prop slip calculator and I am around 6% higher then I was with my Mercury Mirage props.With my G1 300s I was at around 15% slip, now I am at 21%.I am getting my dealer to take another ride with me and swap a few props.
50north

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Posts: 31
Reply with quote  #8 
Intersting! i have been in contact with a guy in Vancouver who runs a 33 grady express and she comes in around 12000Lbs, twin 300's and he hated the rx4- claimed it was a pain in arse at slow speed and reverse so it was a night mare to handle in close quarters. He went to the Merc eco, i think he said 16x19 and he claims it is night and day for his boat.
Again i guess it comes down to the mad science with all the math, crossed with every boat being different, plus every operator/owner knowing how they like to drive!
I drove all sorts of boats from 150 foot to 16 foot and i figured out very fast that they are all different for many different reasons on any given day. Trial and error with a little expert advice seems to be the trick!

I know i never have a reason to be running WOT and i have plenty of HP up my sleeve with the 250's up from the old Fitch 225's so i am looking at the cruising efficiency and  handling/response at close quarters.

let me know what you end up leaning towards and i will keep you posted on what i end up with.

Dean

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Dean
50northadventures.com
50north

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Posts: 31
Reply with quote  #9 
WOW!!!

So this is what i know so far.

We launched early this morning to do the sea trial with the new twin 250's.
No wind, flat water and the BRP tech backing his product and install.

- Grady White 265 express - has a big beam at 9.7, 3 blokes and about 600ltrs on board (hold 900ltr) total around 4 and a half ton of boat!

- RX4 15x20 

- achieved 5300rpm wot at 50knts - put into as harder turn as if operating a ski boat and had no prop blow out and grip to the water like slicks on a race track  

To watch and feel Itrim work and allow the hull to do what it was doing was impressive to say the least.

- Shut down and fully trimmed up the port engine we were able to get up on plain and maintain 16knts at 5300rpm
Massive power

- 4000rpm at 30knts

- 3700rpm at 28knts

At the end the trial we changed out for RX4 15x18 props believing that we will achieve the power band range between 5500/6000rpm as recommended by BRP. I didn't look at anything to do with fuel stats, i will worry about that when we do a few of our tour routes and tank calibrations over the next few weeks.

The power steering mode and response is a game changer and i seriously don't have to touch a trim tab, the engines have the hull so dialled and drive the boat. 

The most impressive part of the entire exercise is how i have been given a new model 265express. It is a completely new boat in regards to response and performance and Grady White would have the perfect boat package if they ever built another 265 express packaged with this power plant.

I will post more as i put a few hours on.



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Dean
50northadventures.com
bottomsup

Registered:
Posts: 51
Reply with quote  #10 
Pulling boat tomorrow and dropping engines 2 bolt holes.This is where my G1 300s were.Also my starboard engine is tilting down on its own.It takes around a day or day in a half and the gear case is in the water.Not sure what is going on but will find out tomorrow.
blackmagic

Registered:
Posts: 130
Reply with quote  #11 
Quote:
Originally Posted by bottomsup
I tried 4 different props I had a set of Mercury Mirage plus on my old G1s 14.5/8x21 At 3500 to 3600 I used to get 33 Mph Now I am only getting 29 and the engines is 1 inch higher then my G1s. I dont have as much trim as I used to and the bow does not feel like it comes up as much.I think I need to drop the engines ???I only used to run my G1s at around 3500 to 3600.Not sure why I lost 3 mph on my old props?  My props are turning inward and I go a little better result by getting on a plane and cutting loose the tie bar.The Rpms on all the props would vary around 150 Rpm and now it only varies buy are 50 to 100. two of the props I got 1 mph faster at 3500 and 4000 Rpm.The difference is around 3/4 of an inch on the tie bar.I had them with a 1/2 of tow with the props further apart.It ended up being a around a 1/4 of tow with the props closer together I also had around 1500 pounds of weight on the boat in fuel and people                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Mercury Enertia ECO  16x21 3 blade
3000 Rpm
Mpg 1.9 Gph 13.6 Mph 27
3500
Mpg 1.8 Gph 18 Mph 32
4000
Mpg 1.5 Gph 18 Mph 37
4500
Mpg 1.3 Gph 32.8 Mph 42
Wide open
5200 Speed 49

Evinrude Rx4s 15x20 4 blade
3000 Rpm I could not get boat to stay on a plane
3500 Rpm
Mpg 1.8 Gph 17.4 Mph 32
4000 Rpm
Mpg 1.6 Gph 23.6 Mph 37
4500 
Mpg 1.3 Gph 31 Mph 41
Wide open
5300 Rpm Mph 49

Evinrude Rx4s 15x18 4 blade 
3000 Rpm
Mpg 1.9 Gph 13.3 Mph 29
3500 Rpm
Mpg 1.9 Gph 15,9 Mph 30
4000
Mpg 1.7 Gph 20.2 Mph 34
4500 Rpm
Mpg 1.5 Gph 25.1 Mph 38
Wide open 5500 Rpm 48 Mph

Mercury Mirage 14-5/8x21 3 blade 
3000 Rpm
Mpg 13.3 Gph 13.3 Mph 25
3500
Mpg 1.9 Gph 15.2 Mph 29 (With same props on G1 300s at 3500 I did32 Mph at 35 to 3600Rpm
4000
Mpg 1.7 Gph 20.7 Mph 34
4500 Rpm
Mpg 1.5 Gph 27 Mph 39
Wide open 5400 Mph 46
   

Specs from Ocean Master 33 Ft with Evinrude G2s On a bracket in stern Also it is around 1000 Lbs heavier then I am
Evinrude Rx4s 4 blade on test 
3000 Rpm Mpg 1.81 Gph 12.5 Mph 26.5
3500
Mpg 2.1 Gph 16.30 Mph 33.5
4000
Mpg 1.77 Gph 22.05 Mph 39
4500
Mpg 1.59 Gph 27.5 Mph 44
5000
Mpg 1.35 Gph 36.7 Mph 49.5
Wide open
5500
Mpg 1.13  Gph 47.5 Mph 54
 


Hmmm.  It is surprising that they saying the 300s turned 5500 on a 33' model using 20" RX4s when you are only able to turn 5300 with the same power and prop on a 31' model.  That would have me wanting more answers.
bottomsup

Registered:
Posts: 51
Reply with quote  #12 
I sent Mark at Ocean Master all my info and he is taking a loot at it.I am going to call him tomorrow.I will see what happen with the engines 1 inch lower.The Rpms are up and down around 100 to 150 rpm with some props and I can t tilt the engines up as much as I use to so it is trial and error.
bottomsup

Registered:
Posts: 51
Reply with quote  #13 
I dropped the engines 1 inch and had an air in the trim and tilt on my starboard engine.I got it out and motor is not dropping down.I also electrolysis starting after one week in the water.I can use the Sea hawk 44 over in the Bahamas.It is just like the old Micron 44.I found the dealer mounted the engines over some of the old paint.I hope that was it? I dod scuff my bracket and put 3 coats of Pettit alumacoat on them and then 2 coats of the Sea Hawk 44.I have done this for over 20 years now with no problems till now.I know that they had to replace one of the positive post in the engine.It got striped out and I was thinking they left a wire off or it is touching some thing on the block.I figured if a wire was left off something would not be working so I hope one of the positive wires in the back side of the positive post is not touching anything.Dropping the boat back in Monday 

 

bottomsup

Registered:
Posts: 51
Reply with quote  #14 
I got it back in the water and did not have time to test out all of the RPMs had to get home and do other things but at 3550 to 3600 I was doing 35 Mph and flashing 1.9 to 2.0 MPH and 17.5 Gph.When the engine were an inch higher I was doing 32 Mph at 1.8 Mpg and 17.4 Gph.
I will go through all of the props again.Btw I was using the 15x20 Rx4s today
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