Inboard prop size

classictrade2 · #1 08-24-2006, 12:32 PM

I forgot to say that I have the 351 ford engine in the boat and I believe it is aroung 250 hp. Thanks for the help.

Classic Trade

Miles Offshore · #2 08-24-2006, 10:15 PM

Hey Author???- I am now turning a 16/15 old ragged spare wheel- the 4 blade was a dog for sure and i would be happy to sell it to any interested party

I am going to by a 16-17 soon and that is what i plan on running- no cup- your wheel sounds fine (the 3 blade) make sure your rpms max out in the 42-4800 range and you should be fine- With lite fuel and the 3 blade i am burning 9 gph and getting 20 to 23 knots depending on tide/fuel etc with 2 people. hope this helps-

classictrade2 · #3 08-25-2006, 02:16 PM

Thanks for the reply. I am planning on posting pictures of my 23 but I am so computer stupid, I am not quite sure how to do it. So I need no cup with the 17x17? I thought a cup was good for the seacraft inboard. I know it is needed in football.

Arthur

riprunner · #4 08-25-2006, 03:02 PM

Miles offshore,

I'm getting around the same speed numbers as you, but I'm burning just a touch more at 10-10.5 GPH. what RPM are you getting that cruise at. I'm at around 3400 and swinging a 15x17 prop. This is also with a new EFI 350 rated at 350hp. I was hoping for a better cruise with that power. Any suggestions?

Miles Offshore · #5 08-25-2006, 09:05 PM

R/R- you should be doing a heck of a lot better than that I think- you have quite a bit more horses than i do- how many rpms is it turning wide open??? I think you might be under propped a little- i think all that extra hp acounts for the little bit extra fuel consumption (maybe) . I normally run between 3K and 3200.

hey Auther- been waiting a while to see pix of your ride!!!!

craig

classictrade2 · #6 08-28-2006, 09:07 AM

I changed out my prop over the weekend to the 17 x 17 3 blade and what a difference. I am now running at a solid 20 knots at 3000 rpms. I think I may need to drop to a 16 pitch because my top rpm on the motor I could achieve was only 3900. I also had a noise and vibration that I have found to be the cutlass bearing. This should be fixed this weekend and then I will see what my top end rpms are and decide about the prop pitch. Thanks a lot Craig for helping me through this.

Arthur

Gary Hill · #7 08-29-2006, 08:26 AM

I have a 350, 315 HP and have a 17 x 16 with a little cup and turn around 4600. At 3000 I'm running 23-24 and burning around 9.5-9.8 gal's per hour. At 3200 I'm running 26-27 and burn 10.5 gal per hour. You need to have it proped so you can turn 46-4800 rpm with a good load in it (full tanks-three people) or the engine is lugging which is not good for it.