Prop Change

C

Chief

New Member
Jan 8, 2007
79
Middle River, MD
Boat Info
2003 349 Sundancer
Engines
Twin 8.1
Was wondering if anyone has changed from a 3 blade to a 4 blade prop. on their inboards.

I am planning to change from the 3 blade to 4 blade over the winter.

I have 2003 340 Dancer with 8.1s v drives.

What I am hoping is that i will get better out of the hole shots, more fuel economy at a lower RPM.

The 3 blade props on there now are 18X21.

Should I change size?
Should I change pitch?
Should I change size and pitch?
Should I keep the same size and pitch, but jsut go to the 4 blade.

thanks

Craig
 
Going from a 3 to a 4 will do all those things you want. I would stay at the same saize/pitch you are now, just with 4 blades.
Most good dealers will let you "try" out different props. And Merc/Quicksilver are good for this. Take a bunch of demo props out, and see what happends. Make a day of it. Yes it's time consumming, but well worth it in the long run to get the right one that will work for you.
 
Ken@dockside said:
Going from a 3 to a 4 will do all those things you want. I would stay at the same saize/pitch you are now, just with 4 blades.
Most good dealers will let you "try" out different props. And Merc/Quicksilver are good for this. Take a bunch of demo props out, and see what happends. Make a day of it. Yes it's time consumming, but well worth it in the long run to get the right one that will work for you.
Click to expand...

+1, same size, just go to 4. Made a difference with our boat.
 
I am also thinking of changing to 4-blade, since my 3-blades need reconditioning anyway. Will probably spend the money on 4-blade and keep the 3-blade for backups if we take a long trip.

My 3-blades are:

1.5" diameter shaft
Starboard: 18" diameter x 18.5" pitch
Port: 18" diameter x 19" pitch

I found this site: http://www.deltaprop.com/shopdisplaycategories.asp?id=302&cat=Inboard+Boats+(4+Blades)

The problem I'm having is that there are too many choices. Can anyone give me recommendations for my size boat and motors?

I've read that trialing various props is a good idea, but I can't imagine how that is feasible unless I had my own hoist. The yards around here charge $250+ just to haul your boat.
 
We had our 4 bladed props tuned about 6 weeks ago. Friday and yesterday was our first opportunity to run the boat since having them re-installed. The boat ran fantastic and I believe our fuel economy has improved.

We did a 3 hour cruise with 1 hour of hull speed on Friday. We have done this same cruse 3-4 times before. We burned 89 gallons of fuel, and most of the trip was against the current. We averaged 3300 RPMs and 23-25 kts.

We did this exact same trip about 4 months ago, same 4 bladed props but not tuned, and we burned a little over 100 gallons of fuel. We had the current with us for most of that trip.

We did the 2nd leg of our trip yesterday, 2 hours, and the boat once again ran fantastic....smooth as a babiys but...little to no vibrations with the 4 bladed props. The fuel economy was great again.

If you are willing to invest the $2000 for 4 bladed props do it.
 
The first year i had the boat i always felt a vibration so during the winter I had them removed and found that MM had installed 2 different props the port had 18x18 and the starboard had 18x18.5. During breakin I consatantly had to run the starboard motor at higher rpm in order to keep a straight course. Also this motor used much more oil than the other. The next season I installed the 4 blade. I think these are the right props. On plan time has decreased and no no no vibration, much smoother. Last season I had them "comp scaned" and the shop had a lot of experience with boats like ours and they added 3/4" .75 cup. Last season the props where even better all performance was enhanced. I was really lucky and pick up the props (nibral Michigan Dqx) for $500.00 from a guy who had them on 38 SR dancer. 4 BLADES ARE THE WAY TO GO.
 
Hello Chief, ? Do you have the classic style 03' 340Da 11'5" beam or the later variant with the 12'0" beam...it makes a difference. If you have the wider style, you should have 18 X 21 4 BC-slight cup. this is a quicker to plane , more fuel efficient solution. Make sure that your RPM's for your 8.1's does not exceed 4600 RPM's.
 
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