Grady Islander performance #'s

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#1
Can anyone that owns one or has the details for me comment?

Max speed and burn rate, cruise speed and burn rate:

- With a single 250 2-smoke both carbed and injected-
- With twin 2-smokers carbed or injected; any power -

Thanks!
 

tunagrady

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#2
I have an Islander 268 with twin fuel injected saltwater series ox66 200's. At cruise, I range between 1.4-1.6, but the most consistent speed seems to be 30 mph, turning at 4,000 rpms, burning 20 gallons per hour, giving me 1.5 mph. The max speed is 45 mph, burning 45 gallons per hour. I hope this helps.
 
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#3
Hi - I am repowering my 1995 268 from a single 250 2-stroke to twin 200 hpdi's. I received the performance data below from Grady White today. Sorry for the format of the information as I was only able to copy and paste. This reply did not allow me to upload the .pdf file. I could fax the original document to you or email it.


GRADY-WHITE PERFORMANCE REPORT
1995 268
Engine: T/200 YAMAHA
Prop: 13 3/4 X 17 M
Test Date
na
ry weight including fuel, persons, gear:
1375
Hardtop/Yes
N 272 W/T/200 YAMAHA
TESTED TESTED TESTED TESTED TESTED
R.P.M. M.P.H. TRIM G.P.H. M.P.G.
1000 6 DOWN 3.2 1.9
1500 7 1 5.6 1.3
D BOAT 2000 8 2 10.4 0.8
OPTIMUM 2500 11 2 12.2 0.9
CONDITIONS 3000 20 2.5 13.0 1.5
3500 29 2.5 18.2 1.6
4000 34 3.0 19.9 1.7
4500 37 3.0 21.2 1.7
5000 43 3.5 27.4 1.6
5300 46 4 38.6 1.2
Engine manuf. top rec. RPM 4500/5500 rpm, Optimum cruise: 29 mph @ 35
M.P.H. TRIM G.P.H. M.P.G.
1000 5.4 DOWN 3.8 1.4
ESTIMATED 1500 6.3 1.0 6.5 1.0
OFFSHORE 2000 7.3 2.0 12.0 0.6
PERFORMANCE* 2500 9.9 2.0 14.7 0.7
3000 18.0 2.5 16.0 1.1
3500 26.1 2.5 21.8 1.2
4000 30.6 3.0 24.0 1.3
4500 33.3 3.0 26.1 1.3
uide on performance.
affect performance:
Wind formance Trim tabssize / condition / type
Current ansducer CurtainsTrolling time
Sea conditi ine trim Tops
Speed om paint Gear placement
 
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#4
Wow. That's awful. How is it that a Voyager that has the same beam, is only ~1.5 feet shorter and weighs only about 6-700 lbs less dry, can be so much better on fuel?

I'm curious to see the numbers for a single 250, but I can't imagine the planing speed and top speed are very good.

Unless I'm missing something, I think you guys have talked me out of having a boat like this for a family fun and fishing. Taking the kids out for a few hours of tubing and playing while burning 40-60 gallons of fuel at $3/gallon sounds nuts to me. :bang
 

tunagrady

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#5
As the saying goes, you have to pay to play. Perhaps you would be better off purchasing a Bayliner with a 130 i/o to take the kids fishing and tubing. It's tough to change the laws of physics. If you want a safe, sturdy, reliable boat to take the family out on, spend the extra few bucks and sleep at night. Just my two cents.
 
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#8
family affair,

Yes my 1995 V-X 250 is carbed. I have a fuel management gauge, however, have not recorded the performance readings.
I'll try to do so this weekend.
 
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#9
abielecki - Thanks. Let me know what you come up with.

BobP - Already have a 20ft overnighter w/ a 200. Too small for what I want, but not yet too painfully expensive to operate! My threshhold is higher, but not 20gph at cruise higher.
 

ocnslr

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Grady White Model
Islander
#10
Islander 270 purchased new in March 2002 with single 250HP OX66. Put 465 hrs on it by Nov 2005, then repowered with twin F150's.

The OX66 was strong, thirsty, reliable, loud, thirsty (yes).... Cruise at 4000RPM was about 22-24kts, getting about 1.2-1.3nmpg. WOT RPM was 5400-5500, at approx 30.5kts, sucking 28gph. Oil use averaged 1gal/33gal fuel for the entire life. Thought about having it made a bit 'leaner', but that can be risky.

The OX66 had no problem spinning a Yamaha SWS 15.25"x17", but there was always excessive prop slip. Went to a PowerTech OFS4 x 17", kept good RPM, and improved "bite" and mid-range performance a bit. Slippage decreased, but still high.

GW never agreed, but I think a single on this boat suffers from aerated (i.e. disturbed) water aft of the two scoop injections mounted just off centerline a couple of feet forward of the transom.

You didn't ask about performance with the F150's, so I won't make you feel bad. I will tell you that we repowered so we would have the range to fish offshore safely - we make 75nm (each way) trips to the Norfolk Canyon with no problem, and we couldn't do that with the OX66.

BTW, our boat is bottom painted, hardtop with curtains almost always up, and performance numbers under real world, loaded conditions.

Finally, we have almost 1000hrs on the twins now, so we do use our boat a lot.

Brian
 

1st grady

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#11
I have a 95 Islander with twin 150 HPDI Yami's. I typically run at 3500 RPM, 25 knots, and see 15 GPH on the flow meter. ( I am happy to see this is less than with the 200's) You really cant go much faster in the ocean anyway and I try to run economical as well. I have bottom paint and hard top and usually loaded with ice, 3 men and gear. Top end is 45 MPH but i didn't want to look at the fuel meter at that speed. We were only able to do this twice in the past two years because of conditions. I don't chart the fuel consumption, I just find a comfortable cruising speed. Tubing and skiing will suck down a lot more fuel when you are doing hole shots all day. I remember using 30 gallons with the 18 footer when skiing and tubing for a few hours. Kids grew up and now it is my turn to have fun. (fishing)