huskyrider

iTrader: (1)

I'm still very green in the offshore powerboating world and am wondering which way to go.
My understanding from my surveyor is that my props are 15" w/ 26 pitch.
Even after lots of searching I'm still confused as which way to move forward on pitch and size
My goal would be hopefully an equal or higher mph cruising speed with a lower rpm. With the gas going up so quickly I'm not going to be banging out top speeds and would rather try to optimize fuel consumption. LMAO at myself for saying that here!!!
Here are my spec's, Baja 38 special, I'm guessing around 10,000 to 11,000 lbs with fuel and gear.
Pair of 525 SC's with intercoolers and the pulley change that offered more boost, powering through B1 outdrives on extension boxes fastened to the transom.
My current top speed last summer was 73 at 5100rpm
With our lake being so low last year I really didn't get any testing time to try to find the sweet spot rpm's before the secondaries kicked in.
As always you guys and girls are absolutely the best source of quality knowledge on these types of powerboats and y'alls advice has been spot on.
I look forward to any insight you may offer.

Thanks,
Kelly

rgrgoog

iTrader: (3)

Kelly, I would stay right were you are at with your 26 pitch 4 blade props. You could try a set of 5 blade 24 pitch props and that may get you a better cruising speed but you may lose some top end. The biggest way to save gas on your motors is to stay out of to much boost. More boost requires more fuel.

4bus

iTrader: (4)

I would take numbers across the board and call a prop guy. 3000-5000 speed at every 500 rpm. If you know someone with a set of 28's try them out and see if you can get on plane. I have a freind that went up in pitch, has no plane probems, has a max rpm now of 4600 but cruise speed is up almost 10mph!

Unlimited jd

iTrader: (5)

did he notice any increase in fuel consumption due to the higher load or is it the same as it was at same speed not neccesarily same rpm? i hope thats clear to someone other than me lol

Mr Gadgets

Another thing to consider is B1 drives with SC motors is hard on the drives. The more pitch/blades you go for, the more load on those drives.. You dont want to gain some fuel mileage at the cost of broken parts..

huskyrider

iTrader: (1)

Thanks for y'alls insight, please keep it coming.
As a novice I'm pretty lost here. After over a year long search for the right boat at the right price I captured a boat with some factory history that was equipped with all the options I wanted in the salon, and powertrains to push this big girl fast enough for me.
I don't remember which member here told me to get ready for piss poor fuel economy because of the 1050's, but he was way correct for sure.
I certainly don't want to overload a pair of 16 yr old drives and be forced to replace or repair them, I'd feel reasonably certain that the riggers at Baja gave due consideration to their mindset when they outfitted the powerplants and drives.
My understanding is that these motors were first generation Team Mercury Racing SC'd engines, they came in at 454cid with a moderate cam and had longevity in mind when they hit the streets. Everything on my boat is totally factory stock as it was campaigned by Baja Marine and sold by Channel Marine to my seller.
My thought process has been to purchase a set of new props or get some smaller carbs and stay out of the high rpm's to avoid a lean A/F ratio. Now after reading 4bus's reply I might consider both and go back with the pulleys that make less boost to keep the cfm down.
I can never tell you folks how much i appreciate the feedback.
If I'm way off track please let me know.

Thanks,
Kelly

dereknkathy

this is the first time i have ever seen fuel economy and 1050 in the same sentence...

Griff

525SC's are going to be thirsty all the time. Swapping props will do very little to help.

Its a catch 22. If you keep the rpms down around 3200, then hull will run wetter with more drag. If you increase the rpms, the fuel will get sucked in faster, but the hull will free up.

huskyrider

iTrader: (1)

Yeah, just as I finished writing that sentence I started laughing at myself for even posting it but I decided not to erase it because if I could keep the gph down even just a little bit it would be worthwhile.


Griff, I certain my hull runs wetted all the time. What I've come to find out is that she's got a foot wider beam than other Mfg's of equal size, no steps, and is heavier than the other Mfg's boats. No wonder she feels so much larger in the cockpit and the salon.
All of the other 38 Specials I considered had 50 to 60 as a top speed. You know, I'm happy with what I've got and I ain't complaining,
but even a little smidgen of less fuel would sure be nice, ROTFLMAO!!!

See ya,
Kelly