3 blade vs 4 blade and rotation info

**Float Funds** · 07-19-2010, 05:28 PM

I have a 1990 350 Searay Sundancer. I have trouble sometimes with cavitation and overall performance in large waves on Lake Erie. The boat has two bravo one stern drives with three blade ss mirage props, 15.25 x 19. My drives are counter rotating; portside turns LH and starboard turns RH. I had a mercury rep tell me to try to go to ss four blade props and changing the linkage on my motors so my rotation would be opposite; portside would be RH and starboard would be LH. He said they found out on larger boats my side they got better performance. What do you guys think about this and what type of ss prop and what size would I go to. Also, what do you think about this rotation change.

Thanks,
Scott

**rondds** · 07-19-2010, 05:32 PM

WOW! Never seen a Pre-clinton 350 with outdrives. Cool!
I have a friend with twin bravo 2 drives on a 2001 maxum 3300. He went to SS three bladers and noticed a HUGE difference in performance compared to the aluminum props. Not sure you're going to need 4 blades, but I do think the change to SS would make a huge difference, without getting into all the changing of rotation stuff.

**Float Funds** · 07-19-2010, 06:25 PM

Yeah they only made 11 with drives. I allready have 3 blade ss props. I am beeing told to go to 4 blade ss props because of cavitation that I get and to give me more trust/power in waves. The rep also sead it would help to change rotation. Just throughing it out there to see what others think and what size and make prop to go with.

**sr330daguy** · 07-19-2010, 07:37 PM

[QUOTE=Float Funds;374644]I have a 1990 350 Searay Sundancer. I have trouble sometimes with cavitation and overall performance in large waves on Lake Erie. The boat has two bravo one stern drives with three blade ss mirage props, 15.25 x 19. My drives are counter rotating; portside turns LH and starboard turns RH. I had a mercury rep tell me to try to go to ss four blade props and changing the linkage on my motors so my rotation would be opposite; portside would be RH and starboard would be LH. He said they found out on larger boats my side they got better performance. What do you guys think about this and what type of ss prop and what size would I go to. Also, what do you think about this rotation change.

Had the same issue with ours,I switched the props to mercury Revolution 4s.Cavitation gone,better acceleration and a couple of MPH increase at cruise speed,top end was the same as the 3 blades I took off.I find the merc reps recommendation interesting.I would like to hear how that works out...

**Float Funds** · 07-19-2010, 08:17 PM

Thats the prop I was thinking of using mercury Revolution
the mrc rep told me to go one pitch lower when I go to a 4 blade and I have now 15.25 X 19 but the revolution is a 14 5/8 X 17 so Idont know what to do.

**sr330daguy** · 07-19-2010, 08:38 PM

Originally Posted by Float Funds

Thats the prop I was thinking of using mercury Revolution
the mrc rep told me to go one pitch lower when I go to a 4 blade and I have now 15.25 X 19 but the revolution is a 14 5/8 X 17 so Idont know what to do.

Try here...www.propgods.com Good forum.Our original props were Mirage Plus 15.25 x 19 .I went with 14 5/8 x19,which maxed the engine at the same 4500 Rpm.

**Skuza** · 07-19-2010, 11:58 PM

I never knew they put outdrives on anything that big! Pics?? Pretty cool as it's rare!

**Float Funds** · 07-20-2010, 11:47 AM

Heres some pics I can"t find any out of water of drives but in one pic you can see one set of controls. With drives I can get in shalow water with drives, also my top speed is about 40mph.

**rondds** · 07-20-2010, 04:18 PM

Float
Boat looks GREAT! LOVE what you've done with the color scheme. I'm a big fan of the monochromatic treatment. NICE!

**EricW** · 07-20-2010, 11:10 PM

Outstanding pictures. That 350 looks fantastic, and the pics have great resolution.

I bet you could throw a party in the bilge of that boat with stern drives. Its really cool that it will hit 40mph.

In the Merc prop lineup, the only real 4 blade alternative to the Mirage Plus is the Revolution 4. I am also curious to know if switching sides for your engine rotations would make a big difference for you.