[bell2132]

Does anybody know what type of 3-blade props come spec with the boat? Our 2002 came with 4 blade props and cruises around 21.8 knots at 2250 RPM. Want to try to regain efficiency and get up to the ~26 knot cruise. If anyone has any other recommendations please let me know as well.

Thanks!

[ReelMagic]

I have a 2003 38 Open w/twin Cummin's 6CTA (450hp) diesel's. The original props are Federal 24x28 3 blade props w/#7 cup..... I also purchased, from Tiara, a spare pair that had the same spec's..That being Federal E/P 24x28 3 blade w/#7 cup .... I assume you have the same engines.... I cruise at 2100 RPM/23.5 knots..... Have had both sets on the boat over the past 10 years and performance has been the same.... Does this help??

[bell2132]

I have a 2003 38 Open w/twin Cummin's 6CTA (450hp) diesel's. The original props are Federal 24x28 3 blade props w/#7 cup..... I also purchased, from Tiara, a spare pair that had the same spec's..That being Federal E/P 24x28 3 blade w/#7 cup .... I assume you have the same engines.... I cruise at 2100 RPM/23.5 knots..... Have had both sets on the boat over the past 10 years and performance has been the same.... Does this help??

Great thank you! Would you be interested in selling the spare props?

[ReelMagic]

Not interested in selling at this point.Will post if a change my mind...

[williamwalter]

I just went through a reconditioning of my props due to being over propped.i have a 480 ce and based on research and conversation I took some pitch off my 24 by 30 props to get my numbers more in line with the 450. From what I found out your fuel flow is key.before reconditioning at 2200 rpm I would do 15.8 gals an hour at 67 percent load doing 24 knots .i now do 13.6 gals an hour and 54 percent load and 24.5 knots at 2200.typically i cruise at 2100 burning 25 gals an hour total and 53 percent load.at wot I'm getting 2680 with load of 88 percent so I'm probably giving up a few knots at wot but never really go there except for testing purposes anyway. Bill

[bell2132]

So I found out the props on the boat are 23x27, I think instead of buying new props I'm going to get them re-pitched and increase the pitch to 28" I'll let you know how it turns out...should be a few weeks as I need to haul the boat and send them in.

[trit21]

i fear you are going about this all wrong. Props are sized not for speed but to ensure rated RPM's can be reached (many cases over rated RPMS's) at full throttle. If you are adjusting props to get more speed, you MAY be overloading the engine and this will cause damage to your engine in the form of dropped valves typically. To much heat in the exhaust which transfers to the drive train and boom. If I have missed something above, please ignore this post, if not, do yourself a favor and only pitch for ++rated RPM at WOT.

[ReelMagic]

I agree w/trit21.. You need to prop the boat so you get Recommended RPM @ WOT... In the case of 450 hp 6CTA Cummin's it's 2600. I get that with 3/4 water & 3/4 fuel. I'm using 24x28 3 blade w/#7 cup.... M2C

[Uhehner]

I agree too.. Most boats are over propped from the factory to start with. If you over load ( over prop ) a diesel it will raise the exhaust temperature and cause all kinds of damage. Plan on a $15K - $20 K repair bill. Just ask my brother with his Cummins. He now has temperature gauges on the exhaust.
You want to reach the rated RPM under an average load of fuel, water and people. Capt. George

[bell2132]

I ended up not re-pitching the props- I only added a slight amount of cup into the props and reconditioned them. The cup in the props took our RPM down from 2700 RPM to 2650 and we were able to pick up roughly 1.5 knots in doing so; we now cruise at ~23 knots which is better than what we were doing previously. Thank you all for your input.