28' 2897 Fuel Math Problem/Advice

C

ChefJunk

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28882
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I am sure that somewhere in the many questions I have had, this has been discussed but I can't find it.

Could any of the 83-90 2987/2827's tell me what they experience as far as fuel consumption at

1. hull speed (i believe 6.9 mph)
2. cruise speed (i believe around 22 mph)

Thanks,

Jim
 
Jim...the '83 thru '90 Mariners varied a bit in economy as Carver changed the trans ratio somewhere in the middle of the model's production run. Later boats will achieve better economy than early ones.
 
TODAY'S MATH PROBLEM:

I found the specs for a 1981 3007 aft cabin that are closest to my boats dimensions. They are as follows:

Data: --- 3007: --- 2897:
LOA --- 29'10 --- 28'0
beam --- 11'4" --- 11'1"
draft --- 34" --- 34"
height --- 11'6" --- 9'11"
weight --- 10,500# --- 10,300#

These are the mechanicals:
engines: --- 220crsdrs --- 230 merc
reduction --- 1.5:1 --- 2.0:1
props --- 18x16 --- 18x19
trans --- straight --- v drive

The performance data for the 3007 is:
RPM - MPH - GPH - MPG
1000 - 5.90 - 1.50 - 3.93
1500 - 7.30 - 3.50 - 2.09
2000 - 8.00 - 6.00 - 1.33
2500 - 13.6 - 10.5 - 1.29
3000 - 18.8 - 14.5 - 1.27
3500 - 23.6 - 20.5 - 1.15
4000 - 27.3 - 25.0 - 1.09
4500 - 29.5 - 36.0 - 0.82

My question is, How would the 2897 do compared to the 3007 based on this info?

Sorry to be so anal about this, I am just trying to figure out if I should take the marina that is 5 miles from the island I like to go to but 30 minute car drive to marina (I do have to go to that area for business once or twice a week). Or, the marina 10 miles from the island but within walking distance from my house (still have to drive to the other marina's area once or twice a week for work).

Thanks for any thoughts!
 
Jim, (purely anecdotally as I dont have have a flow scan) if we're willing to putter along at around 1500rpm we get close to 2 mpg at approx 7 mph. Above 1500 fuel economy drops rapidly. Keeping the boat comfortably on plane with full water/equip/fuel/etc takes about 33-3400rpm. There she's doing apprx 22mph and sipping (more like gulping) 1 gallon per mile. We have the 220 crusaders (unsure of the gear reduction) and we're turning 18x18 props. Hope this helps.
 
Terry,

Do you know if your drives are 1.5 to 1 or 2 to 1? I think they switched from 18x19 props and 2:1 in 1986 and 1987 to 18x18 and 1:5 to 1 in 1988-1990, but I don't know what that means in terms of economy.

Thanks,

Jim
 
Jim, this is the info I pulled from my survey. Not sure if it will help:
Transmissions: “Borg/Warner Velvet Drive” with “Walter” V-drives
Serial numbers:
Starboard: 33121 Port: 33189
· Reduction ratio = 1 to 1

Propellers:
· Twin, Michigan Dyna-Quad three blade bronze propellers that measure 18”diameter x 18”pitch

I'm wondering if the reduction ratio is a typo.
 
I am thinking since you have smaller props and 3 blades, you probably have a 1.5:1 tranny. Mine is 2:1, larger prop, 1 more blade.

I am guessing, purely guessing, that with a smaller prop and more shaft rpm's that it would be similar to a larger prop with 25% fewer shaft rpm's on the same boat.

I hand over the check tomorrow and get a title so soon enough I will be able to see for sure! Assuming I decide where to dock!

Thanks,

Jim
 
Dont think you have the props quite right Jim. As you will see below the 89 also had 4 blade props.

IMG_1798.jpg
 
Actually Jim....let me rephrase that...the surveyor didnt get the props quite right....lol. and hey, good luck tomorrow!
 
quote:
Originally posted by Georgian Bay Cruiser

Actually Jim....let me rephrase that...the surveyor didnt get the props quite right....lol. and hey, good luck tomorrow!

Click to expand...


And to think, surveys are how much a foot? Kind of funny that we hire someone to take a fine tooth comb over a boat and the details most clearly evident are mis recorded, assumed, or just plain guessed at.

Thanks for your help.
 
quote:
Originally posted by RamSport47

Cedar Point Jim!!!!

Click to expand...


I just signed a contract at Dock of The Bay. We'll see how that goes, maybe I will check out CP this summer for next season. I am still frightened by the tolls and traffic!

Jim
 
Dockers don't have to pay the tolls, and you learn the traffic pretty quickly. It's an awesome place to dock for sure.
 
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