Tim's Re-power

franklyprice · Post by **franklyprice** » Mon May 02, 2005 1:47 pm

Doug, You'd be a better judge of what 4 blade props do VS 3 blades but I think it will be pretty hard to improve on those fuel consumption numbers. It will be very interesting to see the results. I've heard good things about those dqx props. If Tim's results are as good as you're expecting , and they may be, I just might have to order a couple of those myself. On a different subject, mine will be in the water next tuesday afternoon(the tenth) It will be intereting to see how the changes I've done effect mine. Frank Price

photo finish · Post by **photo finish** » Mon May 02, 2005 5:19 pm

Doug, its nice to see you are as anal about numbers as i am. and of course i will not keep the props at 4400rpm if that is where they get too.but the prop shop said might as well try them at 20 x20 first because it is not an exact science going between 2 very different props Frank, hurry up and get that boat in the water...and i really want to see how your floors came out someday...i am curious also how your boat runs with your new modifications. Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Tue May 03, 2005 1:06 am

Tim, I'm definately going to have all the flow-scan numbers to compare with yours. I had a couple inches of pitch taken out of the props so I should reach a decent RPM and with the heads being done , it can't hurt the efficiency any but it will be interesting to see if the higher RPMs(but slightly less loading) will hurt or help the GPH. I should know next week. The floors are done with the exception of some trim so as soon as I put the finishing touches on it I'll send some pics. I can say that now that I've been able to clean the boat, and it was more of a mess than I can describe, it looks pretty cool with the floors done. Frank Price

Post by **dougl33** » Tue May 03, 2005 2:53 am

Tim, You're right of course. I would not recommend keeping them if they only turned up 4400rpms. I think 4600rpms is a good mark to shoot for. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA

photo finish · Post by **photo finish** » Tue May 03, 2005 3:37 pm

i ran the boat today with the cupped 20x20x3 and was not happy because i had a vibration i am guessing the prop shop messed up something when they added the cup.so i probably did not get a good read basically i was at 28.8knots at 4550 wot...i hope to get the 4 blades on friday. Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Wed May 04, 2005 1:33 am

Tim, It sounds as though the cup didn't help the top end any, how about cruise or out of the hole? Any advantage to the cup at all? I've heard that if you go to any more than a light to moderate cup, it causes vibration. Frank Price

Post by **dougl33** » Wed May 04, 2005 3:15 am

When I had my 3 blader's recon'd by H&H 2 years ago, they intially put a med cup in. There was no vibration, but the engines wouldn't turn past 3800rpms. I brought them back and they knocked out most of the cup until there was only a "very light cup" (their words). That seemed to do the trick. Still no vibrations and the engines turned right up. Of course 1 year later I wound up throwing a blade. I don't know why, but H&H recommended a cup for our boats as did Tim's prop shop. I don't know the reasoning behind it though. Anyone have an idea as to why? Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA

photo finish · Post by **photo finish** » Wed May 04, 2005 3:26 am

the hole shot was worse and the boat did not plane as well but i am not sure it was the cup i am thinking when the local prop guy added cup he bent a blade...i am not getting my new props from the local guy i am getting them from a guy who has the mri scan machine. Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Wed May 04, 2005 6:02 am

I'm not all that educated about props but I've heard that a cup will help if you're having a problem with cavitation. Frank Price

photo finish · Post by **photo finish** » Sun May 08, 2005 9:31 am

prop data update, put the new 4 blade nibral dqx 20x20s on right out of the box. wot is 4300 4300...31.0 knotts 3720...26.7 knotts 3420...24.3 knotts 3200...22.0 knotts 3050...20.6 knotts 2960...19.0 knotts 2860...18.9 knotts 2650...15.0 knotts 2400...12.9 knotts my idea is to take some pitch out to get my wot at 4600-4650 what do you guys think? crusader says target should be 4600... Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Sun May 08, 2005 12:44 pm

Tim, You're right, you need to take a bit of pitch out , my guess would be about an inch and a half but the prop guys will know. How do you like them overall? Smooth? Any differences that you can tell? I'm really glad you're doing this, what a great bunch of info you're getting for us all.. Frank Price

franklyprice · Post by **franklyprice** » Sun May 08, 2005 12:50 pm

Tim, One more thing. Before you re-pitch the props, it might be a good idea to check the fuel usage at different speeds again. This will tell you how much load your engines are under and you might be surprised to see differences at , say cruising speeds VS the different pitch. Frank Price

photo finish · Post by **photo finish** » Sun May 08, 2005 5:20 pm

frank, i did look at my mpg at different speeds however i did not record too much because i did not like what i saw.if i remember correctly most of the lower speeds were .58-.61 however 3200-3400rpms was .70-.75 mpg...so my guess is that the engines were loaded a little too much..the 2 i did record were at 2860 i got .65mpg and 29gph and at 3720 i got .59 and 44 gph. and yes i did like the way they handled ..the hole shot was amazing and smooth.if the engines were overloaded they sure did not feel or sound that way.great response at docking one thing i am not sure i like is that my slowest idle speed is faster than before it felt like my idle was set higher ...i am not sure if that was the 4 bladers or the fact that the pitch needs to drop a bit. Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Mon May 09, 2005 1:48 am

Tim, Probably a little of both. You've got more surface area on those props , it would stand to reason that you then would also have less slip, especially at slower speeds. Frank

photo finish · Post by **photo finish** » Mon May 09, 2005 3:02 am

Frank, from the numbers do you agree that the rpms should be raised to 4600-4650? Tim Stamm Photo Finish 1981 33' Bertram FBC