2010 Mercruiser 350 MAG BR DTS MPI Prop

V

vortmaximum

New Member
Aug 11, 2015
19
Lake Ontario
Boat Info
2010 Sea Ray 260DB
Engines
2010 Mercruiser 350 Magnum MPI
I have a 260 Sea Ray Deckboat and in the market for a new prop as I've discovered some new to me rock outcroppings....... Currently have the counter rotating Bravo III 48-823665 and 48-823666 24P prop on Drive serial number is OW987782 5441500TS Mercruiser Bravo 3 2.20:1

Each prop I have now has 3 blades. I see new props with a 4 blade/3 blade setup. As I'm new to purchasing props Any thoughts from sea ray experts concerning props? I found this setup: http://greatlakesskipper.com/mercur...itch-stainless-steel-boat-propeller-set-82569 , but clueless what a 4 blade/3 blade combo would do for my speed, handling, fuel, etc compared to my current set up.
 
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All the new prop sets are 4x3. They provide better acceleration, better low speed planing, and less blow out in sharp turns.
If purchasing, I suggest the 4x3 over an old model 3x3.
 
Thanks for the information. I see there are also 4x4 props people have had great success with. It looks like many dropped a pitch size as well with them going from 24 to 22, 22 to 20, etc.
 
I switched my last boat to a 4x4. The reason for the pitch drop is not the 4x4, but because Hill Marine uses a cupped design, and the standard elite series Merc props are not cupped. Cupping reduces RPM by about 200, same as increasing a pitch on the propellers. So if your current props are not cupped, and you switch to cupped, drop a pitch size if your current propellers keep your RPM in the correct range.
 
Thanks again for the information. The more I research the harder the decision. Polished, non polished, cupped, non cupped, pitch, brand etc. A mercruiser dealer suggest the Mercruiser Bravo 3s 4x3 set up with a 22.5 pitch. A quote of 1600+ just for the props. Crazy. I see them for about a grand on line. Decisions, decisions.....
 
There is a guy at Mercury Racing that is a true prop expert. If you call into there, they will help figure out what is optimal for your set up.
 
Do business with someone that will let you exchange them if you're not happy with what they suggest
 
Thanks again. Down to the cupped Mercury quicksilver 4x3 22.5p and the signature cupped 4x4 22p I've been chatting via email with Hill Marine and inquired about some vibration comments I read online. Amazing there isn't more information on the merc 4x3 and or the signature 4x4. Per Hill, "Yes, we did get some bad press around 2013 for vibration issues. We have produced over 20,000 propellers since then with virtually zero issues. As for the propellers, they use all the stock hardware as the OEM propellers. Bolt them on and go...." 20,000 propellers in last 2 years sounds like quite a few to me, they must know what they are doing...
 
I have hill marine 4x4s on my 340 with 496s and they are great props. Track better at slow speeds, back down better and generally better around the docks, plane faster and hold plane a little longer as well.
Defiantly drop a pitch if you are currently running within your WOT rpm range because they do lower Rpms a bit compared to my 3 blade merc props
 
I see we have the same boat. Boat is new to me a couple months ago. Lot of fun to cruise around with. Only issue I had was a bad O2 sensor. Boat had low hours for a 2010, so me running it hard for a few days probably blew some gunk out of the engine. Simple fix. i think I'll give the signature 4x4 props a try for next season. Do you have the DTS throttle? Have you had it calibrated? I have a couple open recall items, mid throttle cable and a camshaft sensor that were never taken care of, but I have no issues with them at this time. Discovering it is a ***** to get a recall taken care of. With a car if you moved across the country you wouldn't have to drive to the original dealer to have a recall addressed. Discovering that's not the case with a boat.
 
Unfortunately the season is over in the North Lands so I haven't changed the props and will wait until next season or a sale on them. I've been tracking my WOT as well over past couple weeks. Last few times out had ~4700+/- RPM on the 3x3 24 pitch factory original props. Engine being WOT rated at 4800 to 5200. With each 1 inch pitch drop netting a gain of ~200 RPMs, sounds like if I go with the 4x4 cupped, a drop to 22s should put right about 4900 at WOTs. Will let you know the results in about 7 months :-(
 
A couple thoughts (to add to all the things you've already been thinking of!)...

--If you're stating your WOT RPM based on your current props... since they're damaged, it's really not a fair and accurate measurement.

--"Spec'd" WOT RPM is based on something like 1/2 tank of fuel, 1 person, minimal gear and totally clean bottom/running gear and near-perfect conditions. Also, trimming up as high as you can go before speed no longer increases or the props ventilate. But that is also one of the reasons there is a range of WOT RPM given - to account for variables. That being, said, if you do get new props I would spec them based on how you "normally" run the boat as far as load is concerned... but you have to get an accurate baseline, first. Dealing with a place that can swap props for you is a definite bonus.

--Props can be fixed - usually at a HUGE savings compared to buying new ones (even ones that are on sale).

--Generally speaking, don't run an engine with damaged props - bad for the drivetrain.

--Depending on how bad of a "hit" it was (and it takes a pretty good hit to do damage to those props), you should consider having the alignment checked this offseason, along with checking for a bent shaft.
 
Correct. All good tips. Current props aren't horrific, but certainly bent the tips a bit. I think I lost 100 RPM or less due to it, but of course amount of gas and weight on boat can impact as well. No vibration on the boat as is. Will have to weigh the cost of new vs repair of 3x3. I like the thought of better gas mileage, handling, maneuvering, lower plane, etc with a 4x4. Thanks for your reply, good info.
 
Along the lines of "better mpg, handling, etc"... There is improvement to be had, but at what cost? In other words, for small gains (it's certainly not a "night and day" difference), what's your "ROI"? Just some food for thought.

I would still get things checked out - hopefully everything is fine - but just because you or your passengers can't feel the vibration, doesn't mean there isn't any.

For what it's worth... I'll assume you use your tabs, but if not... that boat planes out VERY well with the 350MAG/B3 combo. If you use the tabs, it's like it's almost instantaneous. A little exaggeration there, but the tabs make a HUGE difference.
 
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Finally got the boat in the water. Weather has been crap here in Lake Ontario this Spring. I think we had more 60s and 70s in December than April..... New Signature 4x4 props work great. Much better handling around the docks. Less cavitation. At very low speed, less snaking left/right of the boat. Planes out nice at low and top speed. The drop to the Signature 22 pitch from Mercruiser 3x3 24 pitch was perfect. I added about 200 RPM to my WOT. Right in the sweet spot now.
 
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