Four blade props

asher · Post by **asher** » Sun Sep 04, 2016 9:32 am

Anyone running four blades? Thinking about making the switch over from my 3 blades. If so, what's your engine/trans/prop combo. Any information is greatly appreciated. I have a large transom fish box on my 35 that when loaded with ice and fish can almost put the thru hull exhausts entirely underwater. All that extra weight aft is very noticeable as the boat is trying to get up out of its hole. I'm thinking the extra lift from the 4 blades may help alleviate this problem while maintaining good cruise speed with some extra bonuses like cleaner wake and less vibrations. My current setup is 330 cummins qsb's, zf 220a 1.53:1 trans, and 21x22 bronze three blades.

Stafford · Post by **Stafford** » Mon Sep 05, 2016 5:28 am

I am running 4 blade Nibral 22" x 24" With 350 HP Cat 3116's Can't say how the boat ran with 3 blade, but the boat does run smooth and lots of bite. It will dig out of the hole. Runs 23knts at 2300rpm loaded for a canyon trip The props are tuned by Ray @ Atlantis propeller in jersey

Capn Tony · Post by **Capn Tony** » Wed Sep 07, 2016 5:49 am

I just put new 4 blade bronze props on. 21X21 I think they gave them a 40 pitch (have to check the paperwork)dynamically balanced to within 3 grams. New England prop did them. 1.5.to 1 ZF gear. 3116 cats are rated at 2800 rpms. At 2300 running 22 knots 2400 23knts a bit faster with the wind and current and I'm fully loaded. Port @ WOT hits 2835 stbd 2775. I'd like to see a bit more rpm on the stbd. They are smooth and get me out of the hole quickly. The only problem is the slow troll. I have to troll with only one engine in gear. Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

asher · Post by **asher** » Wed Sep 07, 2016 8:45 pm

Thanks for the info so far guys. Tony, I assume those are 350 hp 3116 as well? I've played around with the boatdiesel prop calculator a bit and plugging in the fast displacement hull form with my all the other appropriate variables along with a 27000lb displacement gets me close to my current figures. It then suggests I should run a 20x22 with cup 4 blade. There's nothing wrong with my three blades but I made the mistake of riding on a friend's 35 that had 4's and was very impressed by the way it ran.

Capn Tony · Post by **Capn Tony** » Thu Sep 08, 2016 4:29 am

Asher I checked my paper work from NE Prop. They are a 21X 20 pitch with a 4 cup. Paid $1300 each. Yes they engines are 350HP Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

JohnD · Post by **JohnD** » Tue Sep 13, 2016 7:21 pm

I run 21x26 with a med cup and have 420hp 3126's. You may benefit from spray rails attached to the upper most chine, I can't recall the name. But they are said to add lift and stability on the troll. Let us know how you make out Br,

asher · Post by **asher** » Thu Sep 15, 2016 5:35 am

I've considered the fast rails before and they still may be a reasonable option if I can find a product that is designed to physically attach to the hull and not just glue on. My first step in this process is going to be a haul out and soda blast all the old bottom paint off the bottom. The boat has had non-ablative paint on it for the last 10 years so the buildup is getting pretty extreme. Gonna shed all that weight and then get the current props re-tuned to see where I stand with RPM's and speed. As always I appreciate the input.