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Author Topic:   Exceeding the recomended HP on a new 150 sport
harold posted 02-06-2004 07:12 PM ET (US)   Profile for harold   Send Email to harold  
I'm considering buying a new BW 150 sport in the spring and I have few questions for anyone with some experience or thoughts.

Can I buy just the boat without the motor? I would prefer a Yamaha motor to the Mercury.

Also, what are the ramifications of exceeding the 60hp recommended limit. If I was to put a 70hp or 90hp could it damage the boat? I like the smaller size of the 150, however, I would like to use it for skiing with 4 people in the boat and I'm concerned the 60hp won't handle the job.

Any advice would be appreciated.

lhg posted 02-06-2004 07:54 PM ET (US)     Profile for lhg    
BW has thoroughly tested this boat before setting the HP limit. There is no doubt that a Mercury 60 would handle your waterskiing job, even with 6 in the boat, but whether a Yamaha 60 would is very questionable.

In 2-stroke version, the Merc is definitely a stronger engine. Just check out cubes and alternator output alone. In four stroke version, the Yamaha engine is really a Mercury anyway, but without the quick throttle response and economy of Mercury's EFI system.

Right off the bat, since this is your first post, before this thread ends up joined by the trolls, you should know that you can't get this boat without a Mercury initially. All you can do is make an after-the-sale deal with someone or your Dealer (if he's at all interested, and you are willing to lose the money). Then you could purchase a nice Yamaha 90 for it, even though it won't have much more power than the Mercury 60. Getting a Whaler without a Mercury has been discussed, & even trolled, here endlessly, and we are all now bored with the subject.

Moe posted 02-06-2004 08:18 PM ET (US)     Profile for Moe  Send Email to Moe     
You cannot buy a 150 Sport without a motor or trailer. You would have to sell the motor and replace it with the more powerful one.

The boat has a max motor weight of 305 lbs, which would just handle a 303 lb, 1386cc 90HP Merc Classic (not counting the prop). This a good bit heavier than the 264 lb 60HP four-stroke, but the drain through-hull would probably still be above the waterline when moored if the boat wasn't carrying much.

According to 33CFR183.53, the 15.4' length X 6.5' transom width would result in a factor of 100, which multiplied by 2 and then having 90 subtracted (due to the remote steering), would allow 110 HP if Whaler wanted to rate it that high.

However, they don't (because their 4-stroke and DFI two-stroke 75 and 90 motors are a lot heavier than this). And to exceed the Capacity Plate HP puts you in violation of most state laws, as well as makes it difficult to buy insurance. Some here have found ways to do that, however.

IMHO, 60 HP on this boat is "adequate" for 4 adults, and maybe two _little_ kids, in the boat, PERIOD. IMHO, it could pull one physically fit adult skier with one adult and two kids in the boat, or one kid skier with two adults and a kid in the boat, and that's getting up on two and dropping one if slalom skiing is involved.

I don't feel that 90HP would be too much for the boat as long as you stayed close to the max motor weight limit.
Moe ('03 150 Sport w/60HP 4-stroke EFI BigFoot)

Moe posted 02-06-2004 08:30 PM ET (US)     Profile for Moe  Send Email to Moe     
Let me add...

The 90HP Yamaha is a lot lighter, at 261 lbs, but it's also a lot smaller displacement (1140cc) compared to the 90HP Merc. And for skiing, you want displacement and torque.

If you want a "green" 90HP, the Evinrude 1295cc 90HP E-Tec would do it, at 305 lbs.

But both of these would require replacing the Mercury controls, and _maybe_ the Mercury tach.


Peter posted 02-06-2004 09:12 PM ET (US)     Profile for Peter  Send Email to Peter     
From a weight and displacement perspective, the Yamaha 90 slots in nicely between the Merc 60 and 75/90 2-strokes. I suspect that a Yamaha 90 will perform at least as well as a Merc 75 while at the same time spare the transom more than 40 lbs.
Perry posted 02-06-2004 09:28 PM ET (US)     Profile for Perry  Send Email to Perry     
Any ideas as for top speed on a 150 Sport with a 90 HP?
Moe posted 02-06-2004 09:45 PM ET (US)     Profile for Moe  Send Email to Moe     
I'll leave that to the engineers. A 150 Sport with 60HP is mid-30's.


boxers posted 02-07-2004 12:00 AM ET (US)     Profile for boxers  Send Email to boxers     
I grew up in sticks of Michigan and the prevailing thought regarding internal combustion engines was and continues today to be "more HP is better period". Kinda like the Tim Allen mentality-we built the snowmobile engines (RUPP 440s) to pull the tracks off the frozen ground. We modified our motorcycles and cars in every way possable as well. Some folks even raced their lawn tractors. Bottom line: its a free country so "have at it" the weight limit of the motor should be a concern but the HP you decide upon thats up to you. If it were not for the product liability attorneys then the HP rating would likely be the same is the classic montauk at 90HP given the weight and proportion of the current BW 150 sport. This responce is not politically correct nor a scientific analysis...but life is too short and seldom put a 90HP motor on the back and tell us all about it.

You can buy the hulls without Mercury motors from BW's commercial division but expect to pay more. The smaller BW boats as lhg and Moe mentioned are packaged to be Boat-motor-trailer combinations so the cost of swapping out motors ect. would be significant. It may be better to consider buying a used boat and repowering. Boston Whaler makes hulls which can last a very long time...if properly maintained 40 years or more. Engine technology is constantly changing so the combination of a new outboard on an older hull is quite appealing (and has been implemented by many folks on this site). If you have an interest in that sort of thing you found a really cool website to expand you knowledge of the Boston Whaler legacy. Welcome aboard harold.

harold posted 02-07-2004 09:18 AM ET (US)     Profile for harold  Send Email to harold     
WOW! Thank you all for the responses. First timer to this forum thing, the quick repsponse and knowlage is impressive.

I'm leaning towards leaving well enough alone and using the 60 merc. I'm sure after I get the boat I'll be back in with some questions.

Thanks again.


panther posted 02-07-2004 09:58 AM ET (US)     Profile for panther    
props play a big role in this "ski" equation. less pitch for more out of the hole power, more pitch for top end. four in the boat and a slalom skier would be pushing it. you might also consider a four bladed prop.
Peter posted 02-07-2004 10:07 AM ET (US)     Profile for Peter  Send Email to Peter     
Perry asks: Any ideas as for top speed on a 150 Sport with a 90 HP?

If the 150 Sport will do mid-30s with a strong Mercury 60 then with a 90 HP motor I predict the 150 will go 45 MPH at WOT.

As a point of comparison, a classic 15 loaded with one person and 12 gallons of fuel will go about 37 MPH with a 16 year old 45 cubic inch, 2-stroke, 2 cylinder 50 HP motor. Loaded the same way with a 51 cubic inch, 3 cylinder 70 HP motor mounted all the way down on the transom, the classic 15 will go 43 MPH....plenty fast for most conditions.

JohnJ80 posted 02-07-2004 02:03 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
ah, check with your insurance agent first. some companies insure you, some won't. you don't want to find out the hard way.

My personal opinion, based on a 25 year engineering career, is that with current engineering practices, there are just so many extra considerations with all the computer modeling etc that I would be hesitant to violate the manufacturer's recommendations. There could be circumstances that due to weight, sea state, etc.. that could cause the boat to be unstable and dangerous. It is pretty hard for someone who wasn't involved in the months of design and testing to figure that out on their own.

So, my recommendation, is to not do it.


nolester posted 02-07-2004 03:33 PM ET (US)     Profile for nolester  Send Email to nolester     
Whether you can safely exceed the listed HP limit on a given boat depends on whether the HP limit that is posted is the true safe-operation limit, of course. But one can't assume that to be true.

Just look at the Sport 130. The 2001 model has a capacity plate stating the HP capacity is 30 HP. Yet the next year's model has a plate stating capacity is 40HP. And the boats are otherwise identical.

lhg posted 02-07-2004 03:56 PM ET (US)     Profile for lhg    
Moe - Do you have any information on the relative performance, or does Whaler, of the 2-stroke and 4-stroke 60's. Clark Roberts here seems to really like the 2-stroke version, and says it is strong performer, and not much smoke either.
Moe posted 02-07-2004 05:33 PM ET (US)     Profile for Moe  Send Email to Moe     
Larry, if you look for an older thread about 150 Sports, with "any owners" in the title, you'll find some of that information. Both motors seem to have about the same top speed, with maybe 1 mph in favor of the two-stroke when lightly loaded. I believe the 4-stroke with lower gearing and BigFoot prop will edge the 2-stroke, with a heavier load.

IIRC, the two-stroke gave one member 26-28 miles/tank, while the four-stroke EFI routinely gives us 36-40 according to the distances we cover on the chart. I don't have a GPS yet, so have to use that to determine mileage.

There's a big difference in up-front cost, and it would take forever to make up the difference in fuel. I like the EFI four-stroke for many other reasons, but those with the two-strokes are VERY happy with their setup.

I've been keeping track of 150 Sport owners who crop up here and the mix of 2 and 4 stroke is about 50/50 now, IIRC.


tombro posted 02-09-2004 09:31 AM ET (US)     Profile for tombro  Send Email to tombro     
I'm one of the 2 stroke, 150 Sport owners Moe is referring to. The 60hp gives more than adequate performance for my purposes. In all of my boats, past and present, from 13 to 26 feet, the ability to comfortable cruise @ 23 knots or so in average sea conditions is the goal. This boat delivers that with a dry ride, easily, with the 60 ponies. At WOT, by myself, trimmed up on flat water, it screams, plain and simple. Sips gas, to boot!

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