Props for 31SS
 

What Props are you guys running on a 31 SS?

I have a 97 with 502MPI mags running Brovo 1 26's at 5000rpm's at 72 mph.

Can I get anymore speed with props? I ran those speeds last Oct. with 60 to 70 degree temps in central Pa.

Bravo 1 28's, 72 mph @ 4800 with 496 Mag HO's. I bought some Merc racing lab finished Bravo 1 28's to try if it ever warms up.

Z06, did you ever try out those labbed 28's? I'd be interested in knowing how many RPM's you gained back.

I'm currently hitting the rev limiters with 26 Bravos at 72.1 MPH on GPS, but the temp was only 65 degrees. I think stock 28's might reduce the RPM's too much. Labbed 28's should work at any temp.

My above post with numbers were based on September 07 run. We are better now.

This September with stock Bravo 1 28's, 4950 rpm with trim and tabs at 7. My best so far has been 76 mph with 3/4 fuel, flat water, and 2 aboard with all gear. This is on gaffrig speedometer which I've tested against a Garmin GPS and at 75 it is 74.7 GPS.

My Mercury Racing labbed 28's were for a 32 sunsation that I purchased used. Just minutes after the above run, I ran 77 but the port side was on the rev limiter at 5150 and starboard at 5000 rpm. I'm going to send them back to merc racing propellers this winter for some tuning and hopefully bring the RPM's down and gain another mph...

Modifications since the 2007 run, Hull work to bring back to new condition, Mobil 1 15w-50 in the engines, Amzoil Marine Gear lube in outdrives, removed the turbulators in the exhaust risers, and replaced some worn belt pulleys. The Hull work probably contributed the most but every little thing can help.

My Sonic 31ss with 496 Mag HO's seems to do very well throughout the RPM's with the stock bravo 1 28's.

What RPM's can you turn with your stock 28's on a 90 degree day?

4900 all summer with the stock 28's, no problem, 4950 above was in the evening at about 75 degrees.

With 26p I run 72mph on almost any condition.
Full fuel, four people, full water, bimini top...
I goes up to the rev limiter.

I believe that 28p would be much better. I don't
like hitting the rev limiter.

Warren

Cool, I guess I'll get a set of stock 28's. Thanks. I don't know if Mother Nature is going to let me try them this this year, though.

Gives you time to shop for a good buy or even find someone wanting to trade for your 26's. There has been several stock 28's here in the classifieds in the past for a good price. Another option is to find someone near you that will let you try their 28's before purchasing, although I'm sure you would be happy with the 28's over the 26's. I purchased the used labbed 28's partially just to have a backup set in case a prop gets wacked. With summer just 2-3 months you can't afford to wait for a prop rebuild or delay in a new order.

28's work well, i run 4850 - 4900 stock, i ran labbed 28's and those are perfect. But i am completely stock......I heard removing the turbulators will give a little more rpm.....

Z06 - did you notice any difference when you removed the tubulator plates? Did it become louder? What is the downfall of removing these? Why are they there????

There's some good info on Turbulators in this post...

http://www.offshoreonly.com/forums/s...ht=turbulators

What RPM's did you get with labbed 28's?

If louder, it would take a db meter to tell the difference, but it does sound like a lower (deeper) frequency. Not sure if there was a speed difference because there are so many other factors influencing the speed of our boats. Referenced dyno results on this web site show a 6-10 hp increase after removing the turbulators. If you remove them, just be careful not to let any of the remaining sea water drip out of the riser and into the exhaust manifold below as you remove the exhaust riser elbow. That would result in a downfall. Their purpose as designed by mercury is to trap condensation.

Labbed 28's on my boat did right at 5150. It was perfect.....when I ran them it was a good chop all day (which these boats need), ran great. I think i will take out the plates and see what happens in spring....

I take it that all of you guys have 496ho mags 425hp. And are running 28p. I have 502 MPI mag 415hp, But I am installing GIL exhaust so I should pick up some HP from that ( I hope) lol. Has anyone run 28p with 502MPI 's Like I said earlier I'm peaked out with 26p labbed 5050rpm at 70 to 72 mph depending on the temp.

any input would be nice thanks

Propless,

Call Julie @ Throttle Up and talk it over with her see what her opinion for prop selection would be.

I traded my stock 26P B1's for a set of Mercury labbed 28's and got out today to test them. The temp was only 60 degrees out on the Mississippi River. Downriver, I ran 74.7 and the 496HO's would touch the rev limiters if trimmed beyond 7. Upriver, it ran 73.4. So, the average was 74. That's pretty good, considering the boat has a fridge as well as AC up under the v-berth. Tanks were 1/2 full and two people onboard. I'd still like to get it to 75, though. Previously, I just hit the limiters with the 26's at 72 MPH.

I think the labbed 28's will be good for summer heat. But, I think a set of stock 28's will be better for cooler weather. I always like to have two sets. So, that's the plan.

P.S. I also installed a full set of HPI 9060-PR transom-mount mufflers just last weekend. They really took the edge off the exhaust noise. I could actually talk to my wife while cruising at 3600 RPM.

Plum Crazy
 

What were the water conditions? These boats need a good chop to get them up in the air................

Just a 3" ripple.

2.6 mph increase, good job! Did you notice the labbed 28's being smoother?

Only 2 MPH increase. That's because I was hitting the rev limiters early with the 26's. No real difference in feel with the 28's.

Get into some chop and your doing 76............

Kevin, since you've run both stock and labbed 28's, so you have an impression on whether the 496HO's run better at lower or higher RPM's? Which prop gave you your best speed?

31ss
 

Zo6 You Stated That You Had Your Hull Brought Back To New Condition . Was That A Total Blueprinting Or Just A Little Straighting Here And There. Is The Bottom Perfectly Straight Know If So How Much Was It Out?

There were a few gel coat chips on the inner strakes and some deep scratches that a glass man fixed. He computer matched the color and he nor I could even tell where the work was done. The rest of the hull I buffed with 3M finese it II to remove small scratches and marks from the trailer bunks. These repairs were all needed due to one of the previous owners beaching the boat.

We did not check the hull for staightness with a straight edge. However it looked quite straight by eye once cleaned up.

hmmm... my labbed props feel smoother.

The labbed 28's I ran were the best......i was right between 5K and 5100 and it seemed perfect.
My problem is where i boat - it can get shallow on the chain, so i need the added strength of the non-labbed prop. I will run the labbed props in lake michigan.

Anyone trylabbed 30's.......????

so you guys trim up tp 6-7 on gauge? I was always scared to trim that high , I was only trimming to about 4-5? what are you running tabs at ? I run at 6 the neautral position. I have 28labbed on right now and at those settings I am at 5,000 wot.

Yes, my boat seems happiest at 7. I slowed down below 7 and started to slip above it. I had my tabs up.

Dito here on the trim, I keep the tabs just above 7, that seems to be just high enough to keep them from creating drag. Of course, that makes me wonder how close Sonic set up our gauges from boat to boat?

I always leave the tabs all the way up. Trim out while watching the gps. When speed drops a tenth of two, trim down 1 click and thats the sweet spot. Was about 6.5 on my guage.

I stop gaining about 8 unless it's absolutely glass i'll see like .2mph gain going up to 9 ... but boat is much faster in the **** so all my top speeds are trimmed between 5-7. These boats have about 3/16" hook across the transom and strakes. Forward strake is a little less but still an 1/8" I'm removing all of mine now and blue printing the high speed running surface.