prop size

sbeer · Post by **sbeer** » Mon Mar 29, 2004 3:10 am

Anyone out there running a 33 with 320 h.p cats? I just got the boat last june and I was having a problem with my strb. motor smoking at cruise. I am running 21x24 nibrels. Want to find out if I am over propped. Plan on taking the boat out of the water to do some waork on it in 2 weeks. I want to have the props scanned and if nessasary repitched. Just trying to get a hand on it. Mike

CB35 · Post by **CB35** » Tue Mar 30, 2004 12:51 pm

What gears are you running? I am running 1.5:1 on a 35B with 20X22 Nibral. The only important thing is: are you turning at least 2800 rpm with 2850 being prefeered. The only other thing to check is your No Load rpm. Should be in the 3200 range if I remember correctly. Charlie

sbeer · Post by **sbeer** » Tue Mar 30, 2004 2:03 pm

Is that charlie the road? Your all over the place. Its sea mist. I am pulling the boat 2nd week of april going to put a chunk of cash in her. New bolsters, canvas, rebuilt gen, new formica tops, new hot water heater. Cleaned the motors and painted them. Going to have cat do the work on the motors. I keep getting jerked around waiting for the guys who do it on the side. I found out that they are 1987, installed in florida. The boat originally was built with 454 gas and converted. Thats not to old for diesels. Should be back in the water by 1st of june. Sorry can not make that trip to atlantic city, I will just be getting back from Hatteras. Talk to you later. Mike

CB35 · Post by **CB35** » Wed Mar 31, 2004 2:44 am

Good luck on getting her back into shape. You are going to miss a PARTY. Right now we have 20 boats signed up. They range in size from a 20B to a 63B. You need to cut that trip short to make AC. Good luck Charlie

Diesel Driver · Post by **Diesel Driver** » Wed Apr 07, 2004 9:41 am

I have a 33SF with MAN D0824LE40 engines advertised as 270 HP. 1.53 to 1 ZF gears and run 21 X 24 Nibrals. This prop/gear combination puts the top RPM at 2650 which is just right. I wouldn't think that it would overprop 320HP Cats.

sbeer · Post by **sbeer** » Thu Apr 08, 2004 6:10 am

I have the 320 hp 3208t cats with the 1.53:1 zf gearing. I also run the 21x24 nibrels. The engine at wot under load is supposed to be turning 2800 rpm. on one I only get 2650 and on the other I get 2750. I wanted to find out about prop size because I am taking the props and having them scanned and check with possibly taking an inch of pitch out to see if it brings the 2750 motor up to 2800. I know I have a problem with the other one. While I am waiting for the props I am going to replace all of the injectors to maint. spec to see if that helps [ every 2000 hrs] Thanks

lunderic · Post by **lunderic** » Sat Apr 10, 2004 1:57 pm

I have a 33sf with Cummins 330B (315 HP) and ZF 1.53:1. I an currently using 21X22 3 blade props with a #5 cup. I can turn about 2925 RPMs. I am a little underpropped but I prefer it that way. I would imagine 21X23 would be just about right. Eric

mak6190 · Post by **mak6190** » Fri Apr 23, 2004 6:38 am

I have a 82 Bertram 33SF with Cat3208's 275HP 3000 + hours turning Twin Disc MG502 1.57:1 Nibral 21X22 3 bladed props, 315 gal.of Fuel & 70 gal.of water,6 on board, dinghy with 15 hp Mercury, in other words, fully loaded down which is running about 20.3 - 21.4 kts @ 2650-2700RPM FULL..& 17.3kts. cruise @ 2350 Rpm. When running 1/2 or a 1/4 of a tank of fuel with 4 on board..it will do 2850RPM & Full for 22-23.5 Kts. and have seen 24kts.(rare) and 18.5-19.3 kts. cruise @ 2350Rpm. depending on the wind. In my case it really depends on how heavy I load down the boat. I have always looked on boats.com and yachtworld.com for boats that are for sale with similar arrangements and most of them claim (ball park) 18kts. cruise and 22 tops with CATs 3208 275HP. I have some brass 21X21 3 bladed props for spares and when I checked them out on the boat it lost about 1.5kts turning the same RPM. Hope this info. helps. P.S Props are clean and bare (no anti-fouling paint). You will take a .5kts hit when props are painted.

sbeer · Post by **sbeer** » Mon Apr 26, 2004 10:45 am

with the prop setup I have now, I cruise at 2400 rpm at 23kts. That is with 400gal tank, 5 guys, 70 gal of water. Loaded. At wide open loaded I get the #'s I have said above. I will tell you the truth, If I only got 17 18 kts at cruise, I couldnt take it, way to slow for me. Where I am you got to go 80 miles to get to any good fishing. When I get the props done and back onto the boat I will let everyone know what's up. Thanks, Mike

sbeer · Post by **sbeer** » Thu May 06, 2004 2:50 pm

well got the props back from the prop shop and found that one was 21x22.5 and the other was 21x23.5. These boys were done by 2 diffrent shops. The end result, with alot more work turned out to be unbelievable. I will keep this bad boy. Thanks Mike. By the way I set them at 21x22.5 and they run great.