prop suggestion

[KCMILLS]

23 ft walkaround 200hp evinrude ocean pro currently running a 14 1/4 x 19 aluminum prop uncupped and getting around 37-38 mph with 6000 wot rpm...would like to switch to a 15x17 stainless,,any predictions on what would happen? will i get more speed less rpm's?

 

[walleyehed]

Re: prop suggestion

It would have to be a very old prop to have no cup, and even if it didn't have cup, it should be close speed-wise to a 17 pitch (cupped), which at 6000RPM would be 45-47mph.<br />Your slip ratio figures out to be 34-35%-very, very bad, and I think we may have an indication (gauge) error. Either the tach or the speedo is incorrect and I suspect it's the tach based on the size and type of boat you have.<br />Before you spend any money on a prop, I would either have a shop verify the tach at WOT, and/or verify the speed with a GPS.

 

[KCMILLS]

Re: prop suggestion

speed tach doesnt work on boat the mph figures come off the gps I know probably not that accurate am I going faster than the gps speed you think..I know there is no cup I think its the original prop that came with the motor I have another aluminum prop 14 1/4 x 19 and you can see the cup.the motor certainly seems like it could handle alot more rpm,,,actually i just re-read your reply is gps speed accurate you think?

 

[KCMILLS]

Re: prop suggestion

so my tach is probably wrong then?

 

[walleyehed]

Re: prop suggestion

The tach is WAY off if that is GPS speed.<br />Going WITH GPS speed and a flat 19P slip at 18%, your RPM is only 4700-4800....That's lugging the engine badly.<br />As for that prop coming with the engine, they do not supply a prop with the engine....the dealer installs what he thinks should work, and there is no reason at all to have a flat blade 19 on that combo.<br />The prop is a mis-match, #1., and the tach is not working as it should. I would check the setting on the back and see what # the tach is set to...

 

[KCMILLS]

Re: prop suggestion

can i then change the setting on my tach ? and if i run the motor am i going to hurt it...i have a bid on a 15x17 pitch stainless i thought this would be the right choice this was based on the michigan wheel prop finder ..i filled in the info and this is what was suggested what would you suggest for a prop. I have recently worked on the engine and had to re adjust some things on my carb the boat sounds and seems to run nice with no back firing plugs look good,,so this prop is def wrong or do you think maybe the engine is not up to par?? man i was heading to the ocean tues to fish..

 

[KCMILLS]

Re: prop suggestion

I checked the back of my tach it is set on 2 there are additional numbers up to 5 can you explain this to me and what mine should be set at based on the numbers

 

[walleyehed]

Re: prop suggestion

OK, I believe you have an OMC/BRP tach and the numbers, if you will notice are in this order..<br />2, 3, 4, 6, 5. The slot has an arrow molded into 1 end. The slot if off-center and the arrow is on the opposite end of the slot-look closely. The arrow should be on "6"...this would be exactly accross from "2".<br />The numbers reflect the number of "pulse" or charging coils in the stator.

 

[KCMILLS]

Re: prop suggestion

thank you...learn something new everyday..so that will drop my rpms pretty low then around 4800? my tach set wrong would explain why i had a hard time setting idle,,it all makes sense now....

 

[KCMILLS]

Re: prop suggestion

still on the prop question what prop would you suggest i start with i want stainless so should i go up to a 19 pitch stainless or a 17? the motor is on a gil bracket and is a 25 inch 1996 200 hp evinrude the boat is a 23 wa i usally carry three people and gear it has a 85 gallon gas tank in the floor

 

[walleyehed]

Re: prop suggestion

I think you are way under your target RPM now.<br />If we get the tach verified and know for sure it's working and on the correct setting, I believe I would try the 17 SS, but that may still be a bit low on RPM, but we have options to raise the engine too.

 

[KCMILLS]

Re: prop suggestion

i have read some postings about raising motor height is there a measurement i should take? i have noticed a spray of water on each side of the motor when im running and i thought hmmmm seems like its dragging,,but this is my first outboard im used to inboards.

 

[walleyehed]

Re: prop suggestion

That is an indication of the engine being mounted too low.