Prop Size & speed with a 2 to 1 gear

georgekelly1961 · Post by **georgekelly1961** » Mon Jun 06, 2016 1:35 pm

I have a 35 Bertram with 3208 cats (320 HP)and a 2-1 gear. Please reply back if you have 2-1 gears with prop size and speed info. Need to find the right wheels. She has a 17 knot cruise at 2400 prop is stamped 23 x 26 nibral and turns 2900 wide open at 22 knots.

Chum Bucket · Post by **Chum Bucket** » Fri Jun 10, 2016 10:36 am

Was 2:1 the norm in the 35s? Thought 1.5:1 was fairly consistent in diesel 33s and 35s. Curious. You can definitely add some light cup to what you're running. I have 1,5:1 gears, At 2000-2800 is 20-28 knots respectively.

Pat525 · Post by **Pat525** » Sat Aug 06, 2016 8:21 am

George, I have the same set up as yourself, I have 23/26 4 blades 2400rpm, 20/21 kts ..2800 rpm 26/27 kts

asher · Post by **asher** » Sat Aug 06, 2016 10:56 am

Dirty bottom?

Gccornelius · Post by **Gccornelius** » Sun Aug 07, 2016 3:31 pm

I have 300 hp 3208Ts and cruise 17-19 knots at 2350-2400 rpms and top out at 23-25 knots fully loaded with fuel and water. I have 1.5:1 gears. I plan on getting props refurbished this winter as I have a few dings from the previous owners.

Capn Tony · Post by **Capn Tony** » Tue Aug 09, 2016 2:56 am

Lost a blade on one of my props yesterday. Not sure if I hit something or if it was just stress. I'm running Michigan 4 blade bronze 21/22. I haven't been out of the water in 3 years diver checks me every month during the season. Probably going with 2 new ones if I can get the right price from New England prop. The old props pushed me at 22 knts at 2300rpms 24knts at 2500 but couldn't reach max rpm under load this year (2675rpm). So I started with cleaning the air seps this week the after coolers ........ Hopefully the combo of new props and cleaning the air intake side will do the trick. By the way the engines were tuned last year. If I still can't reach Max after that I'll turn to the injectors. Oh I should mention I can reach. Max at the dock. Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

Capn Tony · Post by **Capn Tony** » Tue Aug 09, 2016 2:18 pm

When I had my props tuned 4 years ago they scanned out at 20.39 and 20.49 not the full 21 inches. I am not sure why but as we know you need 3 inches of clearance between the blade and hull. I need to have the diver measure the clearance on the old props before deciding on what to do with the new ones. I would love to have the room for the full 21 inches. Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

HRay · Post by **HRay** » Wed Aug 10, 2016 6:18 pm

George my 35 (3208Ts) has the 20x22 nibral cupped props which are ones listed in the Bertram spec sheet. were on the boat by previous owner who had them inspected and documented in 2010. I bought the boat two years ago and had them checked and tuned by reputable area shop and sheet said they were actually 21.75 pitch---nothing was changed for prop performance-were declared good condition for continued service. WOT tach 2850 fully loaded 26 kts. Cruise 2400-2500 at 22-23 kts. Seems sweet spot when on plane and where engine sound best. Depending on wind and current will run higher rpm range. As for xtra weight she has hard top n I run her w/ a full enclosure. If you have gauges to compare.....my boost is 8 psi and EGT 875. WOT boost 14 psi and 925 EGT. Double check your tach with a hand held. Those 23x24 wheels turning 2900 loaded has my curiosity. End of day verify your rated WOT and keep them out of lug. Hector

Capn Tony · Post by **Capn Tony** » Thu Aug 11, 2016 3:41 am

Thanks Hector I have a diver coming tomorrow to put on a pair of godfry zincs he will measure the clearance on the existing props. If I have 3.5 inches I'm going with the 21/22 if not I'll have them spec'd by NE Prop to the existing ones. More to come. Meanwhile the after coolers are cleaned painted and ready to be installed today . Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

Capn Tony · Post by **Capn Tony** » Thu Aug 11, 2016 3:46 am

Thanks Hector I have a diver coming tomorrow to put on a pair of godfry zincs he will measure the clearance on the existing props. If I have 3.5 inches I'm going with the 21/22 if not I'll have them spec'd by NE Prop to the existing ones. More to come. Meanwhile the after coolers are cleaned painted and ready to be installed today . Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.

Capn Tony · Post by **Capn Tony** » Fri Aug 12, 2016 2:54 am

Change in plans. NE Prop based on the numbers and performance of the last time we tuned the props recommends I go to a 21inch 20 pitch prop. So Tuesday I'll haul out and put on the new wheels. I will let all know what tHe numbers are. Thanks Capn' T 33'Bert SF 3116 Cats Hyannis MA.