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Author Topic:   1990-1993 25' Walk Around Performance

sblack posted 09-25-2008 06:44 PM ET (US)
I bought and sold a 1992 27' Whaler Walk Around recently for the simple reason that is was a really heavy boat when fully loaded and got poor fuel economy. I am now looking at the 25' model that Whaler made during the same time. The hull weight is almost 2,000# less than the 27 and it's a bit narrower. I know the 27 WA weighed 11,500# fully loaded(official weight scale), and I'm estimating the 25 footer would weigh 7,500# fully loaded. Anyway, looking for any other information from anyone who owns one or knows about this model and it's fuel economy and performance.
cdnwhaler posted 09-26-2008 08:37 AM ET (US)
Dig around the website some more. Most of your questions will be answered. Try here some of the specs.
http://continuouswave.com/whaler/reference/specifications.html
jimh posted 09-26-2008 09:18 AM ET (US)
Since many Boston Whaler classic boats share the same general hull design (of a moderate v-hull nearly constant deadrise), you can assume that their performance characteristics will be generally similar. This leads us to adopt a "hull factor" constant which is nearly the same among those hull designs. We can use the hull factor constant in predicting the performance, along with weight and horsepower. The relationship is explained in the material accompanying my Crouch's Speed Calculator tool at
http://continuouswave.com/cgi-bin/crouchcalc.pl
We can use this to analyze your proposal of changing boats.
For a classic Whaler hull we use a constant of 180. If that hull weighs 11,500-lbs and we wish to push it to a 25-MPH cruise, we can predict the horsepower needed as 222-HP. If we reduce the weight to 7,500-lbs the horsepower decreases to 145-HP. Because fuel consumption is directly related to horsepower, the fuel consumption will decrease in the same ratio, 145/222, or 0.65-times as much fuel.
Converting fuel to horsepower is summarized by the Brake Specific Fuel Consumption (BSFC) of an engine. For a modern outboard motor, typically a direct injection two-cycle or a fuel-injected four-cycle motor, we can use a BSFC of around 0.44-lbs/HP-Hour.
Using the 145-HP needed for our hypothetical 25-footer, we see we will be burning
145 x 0.44 = 64-lbs/hour
Gasoline is typically 6.26-lbs/gallon so we estimate
64-lbs/1- hour X 1-gallon/6.25-lbs = 10-gallons/hour
With a boat speed of 25-MPH and a fuel flow of 10-GPH, we will have a fuel economy of about 2.5-MPH.
Correspondingly, for the heavier boat we would expect
222 X 0.44 = 98-lbs/hour
98-lbs/hour x 1 gallon/6.25-lbs = 15.6-GPH
1-hour/15.6-G x 25-miles/1-hour = 1.6-MPG
These values for fuel economy (1.6-MPG and 2.5-MPG) are targets for optimum performance. They depend on the hull condition, the propeller selection, the running angle, and other influences being optimum, and parasitic drags such as from wind resistance being minimum.
The BSFC figure of 0.44 is also fairly optimistic. It probably represents the peak efficiency of most engines. When run at other than their peak efficiency their BSFC may be higher, leading to poorer fuel economy results.
Many boaters report different results, however it is my experience that most of these anecdotal accounts are based on imprecise measurement of the factors involved (distance and fuel used), and are frequently influenced by owner expectations. There is not too much room for miracles in the conversion of gasoline to boat movement, and most careful studies will produce results that are in good agreement with the figures I have shown above.
Peter posted 09-26-2008 09:28 AM ET (US)
I think the 1990-1993 25 Walk Around with the Accutrak hull form is probably characterized best by a Crouch hull factor number higher than 180 but probably not higher than 200. This will cause a somewhat greater difference than 0.9 MPG predicted.
jimh posted 09-26-2008 09:57 AM ET (US)
Oh, yes, I missed that fact! The Accu-Trak hull probably will have a bit higher performance. I agree.
jimh posted 09-26-2008 10:03 PM ET (US)
With a hull factor constant of 195 assumed for the newer Accu-Trak hull, a 7,500-lb boat going 25-MPH would need 123.3-HP (as calculated by naval architect George Crouch).
To make 123.3-HP with an engine that has a BSFC of 0.44-lbs/HP-Hour we will be burning 54-lbs of fuel per hour, which is 8.7-gallons per hour. This gives us a fuel economy of 2.9-MPG as an estimate for 25-foot Accu-Trak hull.
Thus we can predict (based on fairly sound principles) that a 27-foot classic Whaler will get about 1.6-MPG at cruise with a modern, high-efficiency engine, and a 25-foot Accu-Trak hull will probably get about 2.9-MPG with similarly efficient engines.
andygere posted 09-30-2008 11:10 AM ET (US)
Guys, correct me if I'm wrong, but the 25 Walkaround was not an accutrack hull like the 21 and 23 Walkaround of the same era. It was a Dougherty hull, that most closely approximates a shortened 27. It is a Desert Tan Hull, and came equipped in the full transom WhalerDrive configuration only. Here's a few photos of one:
http://s50.photobucket.com/albums/f344/WhalerTherapy/
themclos posted 09-30-2008 11:54 AM ET (US)
I believe Andy is correct.
Dan
Tom W Clark posted 09-30-2008 12:08 PM ET (US)
The Whaler 25 Walkaround (aka "Widebody") is a classic hull, not an Accutrack hull. It is literally a shortened version of the 27. The Whaler 25 Walkaround is very nearly identical in layout to the Whaler 27 Walkaround.
I cannot see the Whaler 25 Walkaround getting significantly better fuel mileage than the Whaler 27 Walkaround.
If you want a 25 foot Whaler with significantly better fuel mileage, you should be looking at a Revenge 25 Walk Through or Walk Around. This models will get twice the fuel mileage of the 27s if powered correctly.
Peter posted 09-30-2008 02:22 PM ET (US)
Sorry, my mistake, I was thinking they were calling the Walkaround Accutrak hull a 25.
I agree regarding performance of the shortened 27 a.k.a, the 25 Walkaround. It wouldn't be much better on gas than the 27. The problem is the wide beam. Your pushing at least 1 to 1.5 feet x wetted length of additional boat surface along the water surface versus approximately the same wetted length of a 25 Revenge WT or WA.
sblack posted 10-04-2008 08:26 PM ET (US)
Thank you to all of your responses, and you are correct that the 25' Walk Around has a classic whaler hull that is said to weigh in @ 4,600#, with a 9'6" beam. Thankfully I kept my 1989, 25' Revenge (w/o Whaler Drive) that is powered with a 225 Yamaha 4 stroke, and a smaller beam, as you all know. I take long trips on her from San Diego, because unfortunately you have to run 40-100 miles for good fishing from port. I have taken her on 500 mile-5 day trips loaded with extra fuel and ice, and she always gets around 2 statute miles per gallon. I bought a 1991, 27 W/A and was seriously disappointed with the fuel performance of the 2005 Evinrudes. I was hoping that boat was going to take me further, with more comfort and room. One motor was burning 25% more fuel than the other and after 6 months of trying to figure things out with BRP and spending a bunch of money, I decided to sell it, and look at something else. Another disappointment with Evinrude was the XD100 @ $40/gallon. In 6 months I ran the boat 125 hours and used $400 in oil, plus the tanks took up extra storage room. Nothing against Evinrude as they were very helpful and availabe in trouble shooting the problem, but I should have followed my Yamaha gut instinct. No Yamaha, don't buy it. At any rate, I still would like to upgrade to something to get me out and further down the coast of the Baja Peninsula, and I am stuck with my affection of the classic Whaler design. With all of the Yamaha performance bulletins I've read on Grady White and Parker boats of similar weight, size and fuel capacity, I am thinking a 25' Walk Around Whaler should be in the 1.75 statute mile/gallon range, with a pair of Yamaha 250 four strokes. For now, I'll stick with the 25 Revenge/Yamaha and appreciate all of your information.

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Author	Topic: 1990-1993 25' Walk Around Performance
sblack	posted 09-25-2008 06:44 PM ET (US) I bought and sold a 1992 27' Whaler Walk Around recently for the simple reason that is was a really heavy boat when fully loaded and got poor fuel economy. I am now looking at the 25' model that Whaler made during the same time. The hull weight is almost 2,000# less than the 27 and it's a bit narrower. I know the 27 WA weighed 11,500# fully loaded(official weight scale), and I'm estimating the 25 footer would weigh 7,500# fully loaded. Anyway, looking for any other information from anyone who owns one or knows about this model and it's fuel economy and performance.
cdnwhaler	posted 09-26-2008 08:37 AM ET (US) Dig around the website some more. Most of your questions will be answered. Try here some of the specs. http://continuouswave.com/whaler/reference/specifications.html
jimh	posted 09-26-2008 09:18 AM ET (US) Since many Boston Whaler classic boats share the same general hull design (of a moderate v-hull nearly constant deadrise), you can assume that their performance characteristics will be generally similar. This leads us to adopt a "hull factor" constant which is nearly the same among those hull designs. We can use the hull factor constant in predicting the performance, along with weight and horsepower. The relationship is explained in the material accompanying my Crouch's Speed Calculator tool at http://continuouswave.com/cgi-bin/crouchcalc.pl We can use this to analyze your proposal of changing boats. For a classic Whaler hull we use a constant of 180. If that hull weighs 11,500-lbs and we wish to push it to a 25-MPH cruise, we can predict the horsepower needed as 222-HP. If we reduce the weight to 7,500-lbs the horsepower decreases to 145-HP. Because fuel consumption is directly related to horsepower, the fuel consumption will decrease in the same ratio, 145/222, or 0.65-times as much fuel. Converting fuel to horsepower is summarized by the Brake Specific Fuel Consumption (BSFC) of an engine. For a modern outboard motor, typically a direct injection two-cycle or a fuel-injected four-cycle motor, we can use a BSFC of around 0.44-lbs/HP-Hour. Using the 145-HP needed for our hypothetical 25-footer, we see we will be burning 145 x 0.44 = 64-lbs/hour Gasoline is typically 6.26-lbs/gallon so we estimate 64-lbs/1- hour X 1-gallon/6.25-lbs = 10-gallons/hour With a boat speed of 25-MPH and a fuel flow of 10-GPH, we will have a fuel economy of about 2.5-MPH. Correspondingly, for the heavier boat we would expect 222 X 0.44 = 98-lbs/hour 98-lbs/hour x 1 gallon/6.25-lbs = 15.6-GPH 1-hour/15.6-G x 25-miles/1-hour = 1.6-MPG These values for fuel economy (1.6-MPG and 2.5-MPG) are targets for optimum performance. They depend on the hull condition, the propeller selection, the running angle, and other influences being optimum, and parasitic drags such as from wind resistance being minimum. The BSFC figure of 0.44 is also fairly optimistic. It probably represents the peak efficiency of most engines. When run at other than their peak efficiency their BSFC may be higher, leading to poorer fuel economy results. Many boaters report different results, however it is my experience that most of these anecdotal accounts are based on imprecise measurement of the factors involved (distance and fuel used), and are frequently influenced by owner expectations. There is not too much room for miracles in the conversion of gasoline to boat movement, and most careful studies will produce results that are in good agreement with the figures I have shown above.
Peter	posted 09-26-2008 09:28 AM ET (US) I think the 1990-1993 25 Walk Around with the Accutrak hull form is probably characterized best by a Crouch hull factor number higher than 180 but probably not higher than 200. This will cause a somewhat greater difference than 0.9 MPG predicted.
jimh	posted 09-26-2008 09:57 AM ET (US) Oh, yes, I missed that fact! The Accu-Trak hull probably will have a bit higher performance. I agree.
jimh	posted 09-26-2008 10:03 PM ET (US) With a hull factor constant of 195 assumed for the newer Accu-Trak hull, a 7,500-lb boat going 25-MPH would need 123.3-HP (as calculated by naval architect George Crouch). To make 123.3-HP with an engine that has a BSFC of 0.44-lbs/HP-Hour we will be burning 54-lbs of fuel per hour, which is 8.7-gallons per hour. This gives us a fuel economy of 2.9-MPG as an estimate for 25-foot Accu-Trak hull. Thus we can predict (based on fairly sound principles) that a 27-foot classic Whaler will get about 1.6-MPG at cruise with a modern, high-efficiency engine, and a 25-foot Accu-Trak hull will probably get about 2.9-MPG with similarly efficient engines.
andygere	posted 09-30-2008 11:10 AM ET (US) Guys, correct me if I'm wrong, but the 25 Walkaround was not an accutrack hull like the 21 and 23 Walkaround of the same era. It was a Dougherty hull, that most closely approximates a shortened 27. It is a Desert Tan Hull, and came equipped in the full transom WhalerDrive configuration only. Here's a few photos of one: http://s50.photobucket.com/albums/f344/WhalerTherapy/
themclos	posted 09-30-2008 11:54 AM ET (US) I believe Andy is correct. Dan
Tom W Clark	posted 09-30-2008 12:08 PM ET (US) The Whaler 25 Walkaround (aka "Widebody") is a classic hull, not an Accutrack hull. It is literally a shortened version of the 27. The Whaler 25 Walkaround is very nearly identical in layout to the Whaler 27 Walkaround. I cannot see the Whaler 25 Walkaround getting significantly better fuel mileage than the Whaler 27 Walkaround. If you want a 25 foot Whaler with significantly better fuel mileage, you should be looking at a Revenge 25 Walk Through or Walk Around. This models will get twice the fuel mileage of the 27s if powered correctly.
Peter	posted 09-30-2008 02:22 PM ET (US) Sorry, my mistake, I was thinking they were calling the Walkaround Accutrak hull a 25. I agree regarding performance of the shortened 27 a.k.a, the 25 Walkaround. It wouldn't be much better on gas than the 27. The problem is the wide beam. Your pushing at least 1 to 1.5 feet x wetted length of additional boat surface along the water surface versus approximately the same wetted length of a 25 Revenge WT or WA.
sblack	posted 10-04-2008 08:26 PM ET (US) Thank you to all of your responses, and you are correct that the 25' Walk Around has a classic whaler hull that is said to weigh in @ 4,600#, with a 9'6" beam. Thankfully I kept my 1989, 25' Revenge (w/o Whaler Drive) that is powered with a 225 Yamaha 4 stroke, and a smaller beam, as you all know. I take long trips on her from San Diego, because unfortunately you have to run 40-100 miles for good fishing from port. I have taken her on 500 mile-5 day trips loaded with extra fuel and ice, and she always gets around 2 statute miles per gallon. I bought a 1991, 27 W/A and was seriously disappointed with the fuel performance of the 2005 Evinrudes. I was hoping that boat was going to take me further, with more comfort and room. One motor was burning 25% more fuel than the other and after 6 months of trying to figure things out with BRP and spending a bunch of money, I decided to sell it, and look at something else. Another disappointment with Evinrude was the XD100 @ $40/gallon. In 6 months I ran the boat 125 hours and used $400 in oil, plus the tanks took up extra storage room. Nothing against Evinrude as they were very helpful and availabe in trouble shooting the problem, but I should have followed my Yamaha gut instinct. No Yamaha, don't buy it. At any rate, I still would like to upgrade to something to get me out and further down the coast of the Baja Peninsula, and I am stuck with my affection of the classic Whaler design. With all of the Yamaha performance bulletins I've read on Grady White and Parker boats of similar weight, size and fuel capacity, I am thinking a 25' Walk Around Whaler should be in the 1.75 statute mile/gallon range, with a pair of Yamaha 250 four strokes. For now, I'll stick with the 25 Revenge/Yamaha and appreciate all of your information.