2550 RBR with Yamaha SHO 250 results and questions

[rnusr01]

HI,

So now that the motor is broken in I had a chance to really see what she could do this weekend. I am happy with the results but maybe a few of you with more experience could make some suggestions.

I had 3 adults and 3 children on board air temp 80 and water temp 66 at WOT rpm was 6200 and top speed was 43 this is with a Yamaha SS2 15 3/4 x 15. I was thinking about going to a 15 3/4 x 17 for a bit more top speed but not sure if it is worth the cost and what additional top speed I would get. Any input would be appreciated. Thank you.

rnusr01

 

[cwag911]

I would see what the boat does with just you in it and go from there. But looking at the numbers, 6200 with some weight on the boat,  a 16p Enertia would probably do just fine.

 

[Link]

rnus, I think that you are right on with the number you show.  A while ago I researched R models and their various engine sizes as reported in Props & Power with their WOT speed, here is the thread http://club.benningtonmarine.com/index.php?/topic/1965-hp-and-wot/?hl=%2Bbang+%2Bbuck

 

[Rockie69]

http://club.benningtonmarine.com/index.php?/topic/2899-yamaha-250sho-numbers/?hl=rockie69

Here is a thread with "some info. Looks like some think the higher pitch is valid with the higher HP and TomS boat is proof. I intend of going up when I find a good priced prop or a place that will swap.

 

[BulldogsCadillac]

The 15 1/2 x 17 Saltwater series II is what was recommended. The 15 was what was recommended for my 200SHO. Unless that has changed since last year.

 

[RReaume]

You are at the Rev limiter you should be running 5000-6000 rpm with the limiter at 6200. I would say you should go to the 17 pitch to drop some rpm

 

[Chris Z]

In case you haven't seeing this...

http://www.yamahaoutboards.com/sites/default/files/bulletins/bulletin_4stroke_vmax-sho_sws2_bnt_2575rcw_vf250la_2011-10-03_pnt.pdf

I think you're in the ball park. Or at least your set-up sounds similar to what Yamaha has tested. The only thing you have left out is the height of the motor. Is it possible that you're ventilating a bit to get to 6200 rpm?

 

[rnusr01]

No ventilation the motor is a low as it can go and was thinking it could go up a hole or 2 as the plate is a bit under water even on plane. Thanks I will look at that doc

 

[Chris Z]

I didn't notice until just now that you had elipticals like I do. I have  a Yam 150 and it's hanging on hole #2. Had the boat out over Memorial Day weekend and took a good look at the depth of the anti-cavitation plate while I was running about 20 mph. It was just at the surface, you could see the entire plate. That made me very happy, as did the rest of the performance testing that I did while I was out.

I'm very glad that friends that came with me on a "short ride" were understanding as I collected data.

 

[mtudb24]

Chris

The OP (original posters) had the ESP triple toon package unlike your twin eliptical package.  That is how he is running a 250hp motor.

Just making sure we are compairing apples to apples.  BTW, I love my twin elip setup like yours.

 

[jsur]

No ventilation the motor is a low as it can go and was thinking it could go up a hole or 2 as the plate is a bit under water even on plane. Thanks I will look at that doc

Did you ever try the 15.5 by 17 prop?

 

[rnusr01]

No I have not tried any other props