11-foot Boston Whaler Will Not Plane with 9.5-HP

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Author Topic:   11-foot Boston Whaler Will Not Plane with 9.5-HP

Pete Bosheff posted 07-16-2004 10:33 PM ET (US)
I just rescued [an 11-foot Boston Whaler boat] from a garage sale and tried my 9.5-HP Johnson on it. [The 11-foot Boston Whaler boat] would not plane with full-open-throttle, straight tiller, and me almost standing on the bow. What is best power? I am close to purchasing a 15 or 20-HP, mid 1970's for the vintage of the boat. Please advise. [The Boston Whaler 11-foot boat] seems like a very cool boat, but it must perform. We will use it for fishing and fun. Thanks.
ryanwhaler posted 07-17-2004 10:23 AM ET (US)
I had a 8hp Mercury on mine for a short time, and I got it to plane out, but it was prolbey a lot smaller at the time then you are.
I wanted to re-power it, I set out to get a new 20hp Mercury 2 stroke, then found a new old stock, never been started 1990 15hp Mercury on ebay and bought it.
The boat preforums ok with the 15, but with three good sized people it will be hard to plane, with one it flys and with two it go's along pretty good to.
Jarhead posted 07-17-2004 12:40 PM ET (US)
Pete.
Sounds like you've got the not uncommon twofootits already. :)
A 15hp engine should be sufficient to power your new craft with reasonable results.
One thing to keep in mind is your new to you 11' Whaler was designed to perform (or as ryan would say "preforum" :) as a tender. Powering your new prize with an engine higher than it is designed to handle with unreal expectations probably isn't the best idea.
BTW. Good deal on finding an 11 footer at a garage sale.
Enjoy.

ryanwhaler posted 07-17-2004 02:38 PM ET (US)
I have to disagree with Rod.
There is no evidence anywhere that suggests the hull design of the eleven foot whalers was meant to be only a tender.
Many of whalers catalogs from the 1980's show then being used with remote controls, and 25 hp outboards.
Jarhead posted 07-17-2004 04:00 PM ET (US)
You mean besides the fact the tiller model is listed as a Tender?
ryanwhaler posted 07-17-2004 07:41 PM ET (US)
The tender model was the same hull as the Sport and Super Sport, the only difference was the seating and steering.
Jarhead posted 07-17-2004 10:00 PM ET (US)
Pete.
The only information I have is for the 2004 11' models. The 110 Tender (tiller) is rated @ 15hp max. The 110 Sport (remote) is rated @ 25hp max.
Both hulls are identical but you will notice the difference in max. hp rating.
Frankly I believe the only trouble you'd have with a 25 hp engine on your 11 footer is the weight of the engine coupled with your weight at the stern. But then again, what do I know? :)

ryanwhaler posted 07-17-2004 10:55 PM ET (US)
Very little.
Pete,
Since your boat is mid 70s vintage its the older hull, Rod's numbers are irreverent.
The classic eleven foot hull was produced from 1973-1997. The classic hull is lighter and narrower then the current one. It was rated for 10 hp with a tiller and 20 hp when remote steering.
ryanwhaler posted 07-17-2004 11:03 PM ET (US)
Another thing,
Its not necessary for you to worry about the weight of a 25hp motor, as Rod suggests.

The difference in weight between most two stroke 20hp outboards and 25hp outboards is none to nothing. The only difference is the carb. size and the gearing in the lower unit may be different.
Jarhead posted 07-18-2004 12:02 AM ET (US)
Sorry Pete but if ryan insists on showing his ignorance I guesss I'll have to explain the obvious. The difference in weight I referred to was between the 15 and 25hp engines. (about 40lbs)
And as the older hulls are lighter and narrower then the weight difference will be more pronounced.
Side note to the little feller. If I know very little it's still a good deal more than you... :)
Again Pete my apologies. I'll end my part in this now and wish you the best of luck.
ryanwhaler posted 07-18-2004 12:10 AM ET (US)
Interesting, now Rod says he was comparing the 15 hp to the 25 hp, but nothing in his previous post indicates that. You always gotta be right, don't ya, Rodney?
13sport posted 07-18-2004 02:18 PM ET (US)
Jarhead and Ryan,
Don't get started again.
But I have noticed that Ryan's spelling, grammar and sentence structure has improved incredibly in the last few days.
Hey Hooter, do Pod people have advanced English skills?
I’m not sure who you are but you’re not Ryan.
Sport
surveyingdawg posted 07-18-2004 05:57 PM ET (US)
I have an 197611 with a 25 with remote controls. Have seen many with 30 and even one with a 40 mercury. IMHO the 25 is barely adequate on my boat. With 2 full size adults the boat struggles to plane. This boat is definietly not just a tender.
13_Dauntless posted 07-21-2004 04:40 PM ET (US)
I had an 11' Sport with a Johnson 20 and remote controls. It would run 25 mph WOT, but with a lot of weight in the boat it would struggle to plane. If I had another, I wouldn't hesitate to run 30 hp on it.
ryanwhaler posted 07-21-2004 09:55 PM ET (US)
It these post classic eleven's are very weight sensitive, regardless of house power.
Like I said, when I’m by myself in mine, it screams. Load her up with a few good sized people and its a dog.
Bigshot posted 07-22-2004 11:22 AM ET (US)
Problem with the 11' is it is 11'. A 13' will be faster and plane better than an 11'. These wetre designed to be tenders but became pretty popular as a runabout, problem was they were not much cheaper than the 13' hence why most were only bought as tenders(as in T/T). If you get a 15, or 30hp, get a tiller extension so you can sit on the middle twart.
whalersailer posted 07-22-2004 02:28 PM ET (US)
I currently own a 1995 11 Tender with a 2000 Yamaha 15 2S. I have also owned an 11 Sport with a Johnson 25.
I never pulled performance numbers off the Sport, but she performed very well with the maximum weight aboard (per the hull capacity tag).
A few weeks ago we were out fishing in the Tender. With 2 grown men (440# total), my 4 year old (40#), cooler, full gas, and fishing gear, the boat pulled 18.8 knots on my WAAS GPS (21.6 MPH). The boat was sluggish to plane (my buddy had to move pretty far forward), but I was pleased with the performance given that the boat was overloaded (per the capacity tag).
With an 11 Tender, I would not want any more weight on the transom than the 90# or so that a 15 2S weighs.
With controls, wheel and slightly forward helm station, I feel that 25's are a perfect match for the 11 Sport.
That's my experience and opinion - hope it helps!
-WS
Bigshot posted 07-22-2004 03:02 PM ET (US)
PS...those old 9.5's are closer to 6-7hp per todays engines. My friend had one on his identical 12' Alum boat and my 7.5 Johnson (1983) was just as fast if not faster.
Pete Bosheff posted 07-22-2004 07:27 PM ET (US)
Thanks to all you who have replied to my questions about powering the 11.5. We took it out Sunday w/ the 9.5, after I did a quick tune-up, fresh fuel and trim testing and it did pretty well actually.
FYI we have an awesome resource in Grand Rapids MI for outboards - Van's - which should be a destination at least once in every boater's lifetime. They are extremely capable, have what seems to be a thousand outboards of every vintage - for sale - w/ warranty in the backroom. They have been extremely helpful. I will probably get a 20 ss but am open minded about a 25 or a 15 for that matter.
It is very interesting the variety of comments and opinions about what powers this boat correctly. In any case, please continue forwarding information. We really love the little boat and will continue testing.
I try not to keep alot of "stuff" around - and have no interest in big boats. That said, I have decided to keep the 9.5 Johnson and add a bigger motor. I acually bought the 9.5 with my own money when I was 14. Some sentimental value + I put every hour on that motor since new. Cool huh?
best to all and thanks - keep the info coming.
whaler131 posted 07-22-2004 10:56 PM ET (US)
I have a 1988 11 that I made into a center, I put a 9.9 1990 johnson on it, and I can get on plane, and go 17 mph. with 6 gal of gas and fishing equipment and all the rest of the wood. The boat looks like my old 17 super sport . If I put two adults in it she really slows down.. I am real happy with her.
Rob1717 posted 05-02-2010 04:24 AM ET (US)
I have a 1975 11-foot whaler with 9.9-HP Johnson. I run a three-blade 9.25 by 8-inch pitch propeller, and it planes well with 240 lbs. (me). It tops out at 21.1-MPH. With my 125-pound wife with me it runs 19.0-MPH, but is sluggish to plane. Still, for 9.9-HP, [the 11-foot Boston Whaler boat] is a decent runner. The stock 10-inch propeller has too much pitch to work well. The engine can turn an 8-inch pitch to some serious RPM and produce all 9.9 H.P. A 9-inch pitch will work with one person and tops out at 21.5-MPH.
Stevebaz posted 05-03-2010 07:06 PM ET (US)
My 1979 SPORT 11 with cable steering is supposed to be 20-MP maximum. A standard tiller steer is supposed to be 15-HP maximum. My 1979 SPORT 11 is powered with a 1982 Mercury 25-HP that weighs 113-lbs. With 600-lbs (or 2 adults, a dog, the fuel the and gear) additional weight in the boat, I have [measured] almost 27-MPH. For me this is scary fast in such a little boat with such a low water line. Jumping up on plane is not [difficult]. Slowing down and the wake catching up and over the transom is a [concern]. Steve
Tohsgib posted 05-04-2010 01:30 PM ET (US)
Why somebody is rehashing a 6 year old thread is beyond me but...tiller is 10hp max, not 15.
Tollyfamily posted 05-06-2010 04:51 PM ET (US)
I have a 1975 11' (hull #7) with a 28SPL (it's really a 30) and it will plane with 2 adults, 2 kids and a dog in front and runs 31 mph at 5800 rpm with 2 people aboard. This seems to be a perfect setup and is in no way overpowered. The boat sits almost level with the #118 motor, the fuel tank is in front of the forward bench and the battery in under the console. There are about a dozen similar boats at my club and the most common engine is a 20, one has a 15 but won't plane with 2 adults.
http://s101.photobucket.com/albums/m56/Finnelly/?action=view¤t=Readyforseatrial.jpg
PeteB88 posted 05-12-2010 07:16 PM ET (US)
WOW - wow.

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Author	Topic: 11-foot Boston Whaler Will Not Plane with 9.5-HP
Pete Bosheff	posted 07-16-2004 10:33 PM ET (US) I just rescued [an 11-foot Boston Whaler boat] from a garage sale and tried my 9.5-HP Johnson on it. [The 11-foot Boston Whaler boat] would not plane with full-open-throttle, straight tiller, and me almost standing on the bow. What is best power? I am close to purchasing a 15 or 20-HP, mid 1970's for the vintage of the boat. Please advise. [The Boston Whaler 11-foot boat] seems like a very cool boat, but it must perform. We will use it for fishing and fun. Thanks.
ryanwhaler	posted 07-17-2004 10:23 AM ET (US) I had a 8hp Mercury on mine for a short time, and I got it to plane out, but it was prolbey a lot smaller at the time then you are. I wanted to re-power it, I set out to get a new 20hp Mercury 2 stroke, then found a new old stock, never been started 1990 15hp Mercury on ebay and bought it. The boat preforums ok with the 15, but with three good sized people it will be hard to plane, with one it flys and with two it go's along pretty good to.
Jarhead	posted 07-17-2004 12:40 PM ET (US) Pete. Sounds like you've got the not uncommon twofootits already. :) A 15hp engine should be sufficient to power your new craft with reasonable results. One thing to keep in mind is your new to you 11' Whaler was designed to perform (or as ryan would say "preforum" :) as a tender. Powering your new prize with an engine higher than it is designed to handle with unreal expectations probably isn't the best idea. BTW. Good deal on finding an 11 footer at a garage sale. Enjoy.
ryanwhaler	posted 07-17-2004 02:38 PM ET (US) I have to disagree with Rod. There is no evidence anywhere that suggests the hull design of the eleven foot whalers was meant to be only a tender. Many of whalers catalogs from the 1980's show then being used with remote controls, and 25 hp outboards.
Jarhead	posted 07-17-2004 04:00 PM ET (US) You mean besides the fact the tiller model is listed as a Tender?
ryanwhaler	posted 07-17-2004 07:41 PM ET (US) The tender model was the same hull as the Sport and Super Sport, the only difference was the seating and steering.
Jarhead	posted 07-17-2004 10:00 PM ET (US) Pete. The only information I have is for the 2004 11' models. The 110 Tender (tiller) is rated @ 15hp max. The 110 Sport (remote) is rated @ 25hp max. Both hulls are identical but you will notice the difference in max. hp rating. Frankly I believe the only trouble you'd have with a 25 hp engine on your 11 footer is the weight of the engine coupled with your weight at the stern. But then again, what do I know? :)
ryanwhaler	posted 07-17-2004 10:55 PM ET (US) Very little. Pete, Since your boat is mid 70s vintage its the older hull, Rod's numbers are irreverent. The classic eleven foot hull was produced from 1973-1997. The classic hull is lighter and narrower then the current one. It was rated for 10 hp with a tiller and 20 hp when remote steering.
ryanwhaler	posted 07-17-2004 11:03 PM ET (US) Another thing, Its not necessary for you to worry about the weight of a 25hp motor, as Rod suggests. The difference in weight between most two stroke 20hp outboards and 25hp outboards is none to nothing. The only difference is the carb. size and the gearing in the lower unit may be different.
Jarhead	posted 07-18-2004 12:02 AM ET (US) Sorry Pete but if ryan insists on showing his ignorance I guesss I'll have to explain the obvious. The difference in weight I referred to was between the 15 and 25hp engines. (about 40lbs) And as the older hulls are lighter and narrower then the weight difference will be more pronounced. Side note to the little feller. If I know very little it's still a good deal more than you... :) Again Pete my apologies. I'll end my part in this now and wish you the best of luck.
ryanwhaler	posted 07-18-2004 12:10 AM ET (US) Interesting, now Rod says he was comparing the 15 hp to the 25 hp, but nothing in his previous post indicates that. You always gotta be right, don't ya, Rodney?
13sport	posted 07-18-2004 02:18 PM ET (US) Jarhead and Ryan, Don't get started again. But I have noticed that Ryan's spelling, grammar and sentence structure has improved incredibly in the last few days. Hey Hooter, do Pod people have advanced English skills? I’m not sure who you are but you’re not Ryan. Sport
surveyingdawg	posted 07-18-2004 05:57 PM ET (US) I have an 197611 with a 25 with remote controls. Have seen many with 30 and even one with a 40 mercury. IMHO the 25 is barely adequate on my boat. With 2 full size adults the boat struggles to plane. This boat is definietly not just a tender.
13_Dauntless	posted 07-21-2004 04:40 PM ET (US) I had an 11' Sport with a Johnson 20 and remote controls. It would run 25 mph WOT, but with a lot of weight in the boat it would struggle to plane. If I had another, I wouldn't hesitate to run 30 hp on it.
ryanwhaler	posted 07-21-2004 09:55 PM ET (US) It these post classic eleven's are very weight sensitive, regardless of house power. Like I said, when I’m by myself in mine, it screams. Load her up with a few good sized people and its a dog.
Bigshot	posted 07-22-2004 11:22 AM ET (US) Problem with the 11' is it is 11'. A 13' will be faster and plane better than an 11'. These wetre designed to be tenders but became pretty popular as a runabout, problem was they were not much cheaper than the 13' hence why most were only bought as tenders(as in T/T). If you get a 15, or 30hp, get a tiller extension so you can sit on the middle twart.
whalersailer	posted 07-22-2004 02:28 PM ET (US) I currently own a 1995 11 Tender with a 2000 Yamaha 15 2S. I have also owned an 11 Sport with a Johnson 25. I never pulled performance numbers off the Sport, but she performed very well with the maximum weight aboard (per the hull capacity tag). A few weeks ago we were out fishing in the Tender. With 2 grown men (440# total), my 4 year old (40#), cooler, full gas, and fishing gear, the boat pulled 18.8 knots on my WAAS GPS (21.6 MPH). The boat was sluggish to plane (my buddy had to move pretty far forward), but I was pleased with the performance given that the boat was overloaded (per the capacity tag). With an 11 Tender, I would not want any more weight on the transom than the 90# or so that a 15 2S weighs. With controls, wheel and slightly forward helm station, I feel that 25's are a perfect match for the 11 Sport. That's my experience and opinion - hope it helps! -WS
Bigshot	posted 07-22-2004 03:02 PM ET (US) PS...those old 9.5's are closer to 6-7hp per todays engines. My friend had one on his identical 12' Alum boat and my 7.5 Johnson (1983) was just as fast if not faster.
Pete Bosheff	posted 07-22-2004 07:27 PM ET (US) Thanks to all you who have replied to my questions about powering the 11.5. We took it out Sunday w/ the 9.5, after I did a quick tune-up, fresh fuel and trim testing and it did pretty well actually. FYI we have an awesome resource in Grand Rapids MI for outboards - Van's - which should be a destination at least once in every boater's lifetime. They are extremely capable, have what seems to be a thousand outboards of every vintage - for sale - w/ warranty in the backroom. They have been extremely helpful. I will probably get a 20 ss but am open minded about a 25 or a 15 for that matter. It is very interesting the variety of comments and opinions about what powers this boat correctly. In any case, please continue forwarding information. We really love the little boat and will continue testing. I try not to keep alot of "stuff" around - and have no interest in big boats. That said, I have decided to keep the 9.5 Johnson and add a bigger motor. I acually bought the 9.5 with my own money when I was 14. Some sentimental value + I put every hour on that motor since new. Cool huh? best to all and thanks - keep the info coming.
whaler131	posted 07-22-2004 10:56 PM ET (US) I have a 1988 11 that I made into a center, I put a 9.9 1990 johnson on it, and I can get on plane, and go 17 mph. with 6 gal of gas and fishing equipment and all the rest of the wood. The boat looks like my old 17 super sport . If I put two adults in it she really slows down.. I am real happy with her.
Rob1717	posted 05-02-2010 04:24 AM ET (US) I have a 1975 11-foot whaler with 9.9-HP Johnson. I run a three-blade 9.25 by 8-inch pitch propeller, and it planes well with 240 lbs. (me). It tops out at 21.1-MPH. With my 125-pound wife with me it runs 19.0-MPH, but is sluggish to plane. Still, for 9.9-HP, [the 11-foot Boston Whaler boat] is a decent runner. The stock 10-inch propeller has too much pitch to work well. The engine can turn an 8-inch pitch to some serious RPM and produce all 9.9 H.P. A 9-inch pitch will work with one person and tops out at 21.5-MPH.
Stevebaz	posted 05-03-2010 07:06 PM ET (US) My 1979 SPORT 11 with cable steering is supposed to be 20-MP maximum. A standard tiller steer is supposed to be 15-HP maximum. My 1979 SPORT 11 is powered with a 1982 Mercury 25-HP that weighs 113-lbs. With 600-lbs (or 2 adults, a dog, the fuel the and gear) additional weight in the boat, I have [measured] almost 27-MPH. For me this is scary fast in such a little boat with such a low water line. Jumping up on plane is not [difficult]. Slowing down and the wake catching up and over the transom is a [concern]. Steve
Tohsgib	posted 05-04-2010 01:30 PM ET (US) Why somebody is rehashing a 6 year old thread is beyond me but...tiller is 10hp max, not 15.
Tollyfamily	posted 05-06-2010 04:51 PM ET (US) I have a 1975 11' (hull #7) with a 28SPL (it's really a 30) and it will plane with 2 adults, 2 kids and a dog in front and runs 31 mph at 5800 rpm with 2 people aboard. This seems to be a perfect setup and is in no way overpowered. The boat sits almost level with the #118 motor, the fuel tank is in front of the forward bench and the battery in under the console. There are about a dozen similar boats at my club and the most common engine is a 20, one has a 15 but won't plane with 2 adults. http://s101.photobucket.com/albums/m56/Finnelly/?action=view¤t=Readyforseatrial.jpg
PeteB88	posted 05-12-2010 07:16 PM ET (US) WOW - wow.