Outboard horsepower debate

[hempfarmer]

How do you guys determine outboard horsepower needs for a ski boat?

Example: 750 LBS 16 foot fiber glass ski boat.

Would you say a 115 two stroke is adequate for pulling 250 pound grown men?

I hear varying opinions from the people on my lake. I know you could pull people with smaller engines but would that eventually put too much stress on a 2 stroke causing you to have problems down the road?

 

[Chris1956]

Re: Outboard horsepower debate

Let's decompose the question a bit further. Are you planning to pull a salom skiier at 36MPH, or a combo skiier ate 27 MPH?

What is rating for hull?

Do you want minimum power fot this, max power for this or something else? With the correct prop, even a small motor can generate adequate power.

A 115HP motor on that boat will pull a salom skiier with the two men you cite, aboard. Prop it to reach max RPM at WOT with three aboard, and you should be OK

 

[hempfarmer]

Re: Outboard horsepower debate

Let's decompose the question a bit further. Are you planning to pull a salom skiier at 36MPH, or a combo skiier ate 27 MPH?

What is rating for hull?

Do you want minimum power fot this, max power for this or something else? With the correct prop, even a small motor can generate adequate power.

A 115HP motor on that boat will pull a salom skiier with the two men you cite, aboard. Prop it to reach max RPM at WOT with three aboard, and you should be OK

I am looking for flexibility, able to pull either type of skier and either speed. Hull is rated for 125 HP.

Let's say you have a mid 90's Merc 115HP 4cyl and a mid 90's Merc 150HP V6, it sounds like they both can do the job. But since the 115HP is working harder is it safe to say it would experience more wear and tear since it has to run at a higher RPM? Provided both engines are well maintained would the higher horsepower engine last longer?

Really just trying to determine if there is a long term benefit having a slightly more powerful engine then what your hull is rated for. Especially when a boat is used mainly for watersports.

 

[Frank Acampora]

Re: Outboard horsepower debate

In skiing, too much horsepower is never enough!

Outboards are made to run at or near full throttle all the time. It is not a question of wear or stress on the engine, but wear on the skier.

With a deepwater start, the larger engine with more torque will pop out the skier onto a plane faster, thereby putting less stress on his arms. This becomes even more important if the giant behind the boat is trying to slalom ski.

If your boat is rated for 125, the 115 will be adequate, but only that. A 125 would give you much better performance.

You did mention a Merc 150. Now, the moderators get angry if we recommend overpowering a hull and there are definite legal ramifications to doing so, especially if you have an accident, but in the end, you will do what you want.

 

[Bob_VT]

Re: Outboard horsepower debate

Water skiing will place allot of stress on the hull/transom.......... a good skier can raise havoc with the boat and motor. I have done deep water starts behind a 16' boat with a 55 hp. .......... allot depends on the skill level of the skier. The 115 will suit you fine.

 

[metriccrescentwrench]

Re: Outboard horsepower debate

My "other" boat is a 15 ft fish-n-ski with a 1980 Johnson 90. That's got plenty of ooomph to get skiers up, and even with 3 or 4 people in the boat. I'd say that 115 on a 16 ft boat will do fine. As already mentioned prop it to wind up to it's rated WOT rpms, or even get a second, lower pitched "ski" prop to put on for water sports.

 

[Nutron]

Re: Outboard horsepower debate

I run a 16ft Glastron with a 115hp 2 stroke Johnson. My family and I wakeboard and I can tell you from experience as long as you plane your engine just right there is plenttttyyyyy of power with the 115. I went from a 19 pitch to a 17 pitch prop and the wot for this engine is 5500rpm and it runs wot at 5500 to 5600 with a 17 pitch. The 19 was around 4900 to 5000. I hope this helps.

 

[Frank Acampora]

Re: Outboard horsepower debate

I have also deepwater started on slalom behind the 15 foot boat in the avatar with a 55---but I don't weight 250. And, I didn't like it. Tough on the arms and legs and tough on the boat too. That's why the boat now has its max rated 90 horsepower. Much better to ski with.

 

[hempfarmer]

Re: Outboard horsepower debate

You see smaller 16ft fiberglass boats for sale all over the place that have old 150 or 200 Merc Black Max engines. There is no way anyone of them have a HP rating that high. Is this because I live in Canada?

 

[V153]

Re: Outboard horsepower debate

When it comes to older boats this is kinda a grey area. For example: The plate on my '71 V153 states: "This boat is built to accomodate under normal conditions an outboard motor of not more than 90hp and 6 persons at 150 lb per person." "OR" "A properly located max wt of 1335 lbs for persons. motor and gear." Okay, what does "or" mean?

Not to suggest anyone rush out and grossly overpower their boat but a lil extra hp never hurt when used in moderation. If your insurance co gives you any crap hang up & go with a company that specializes in classic/performance vehicles.

Bears mention stupidity ranks first in boating accidents. Followed closely by intoxication. Granted excessive speed can be a factor. But depending on the situation at hand just about any boat can travel at an "excessive speed".

It pains me to see folks browbeaten by insurance companies. Read racketeers. The water cops around here couldn't care less what ya got for power. Cuz most of their boats are overpowered anyway?

 

[Nutron]

Re: Outboard horsepower debate

If you have a boat that is 16' and rated for a 90hp max, say you put a 185 on there.... wouldn't you do some serious damage to the transom or just rip it off? I have a 16' rated for 90hp max and I just recently put a 115hp motor on it, I have a 185 v-6 Johnson I thought of putting on there, but the mechanic told me I would rip of the transom by putting to much motor on. He said the 115 was good enough. Only I get more speed from the 90 that blew up than the 115 I just put on, it seems there is more torque with the 90.

 

[HT32BSX115]

Re: Outboard horsepower debate

If you have a boat that is 16' and rated for a 90hp max, say you put a 185 on there.... wouldn't you do some serious damage to the transom or just rip it off?

Maybe, maybe not.

Most boats will "handle" a LOT more HP than the placard indicates......and NO engineer would design a boat and rate the HP to "break" the boat at a power rating only slightly above placarded HP..........

However, if you DO have a MUCH higher HP engine on the boat, (like you indicated above, DOUBLE the placard rating) and you do "break" it......... there's a few possibilities:

If you have insurance, and the insurance company finds out that you intentionally installed the engine, they may not cover you.
(and I'm not talking about high HP race boats here....)

If someone dies, and the survivors lawyer finds out (they call it "Discovery") that you intentionally installed an engine at double the HP rating, you WILL be sued for reckless endangerment, your insurance company will probably not cover you, (or only cover you up to the limit of your liability........which means you will LOSE your house!!!), AND you may go to jail.

By the way, iboats like ALL other forum sites will reveal ALL of your posts on this board to a lawyer if a court orders it. (I hope you don't think you're anonymous here.........your IP address, internet provider and YOU can be easily identified)


And if you sold the boat to someone else, and they killed someone, they would get sued AND the surviving family's lawyer would probably go looking for anyone else who was involved in it like the previous owner, and maybe the boat repair facility that might have installed the engine....... Which is why you'll NEVER find anyone in business that will agree to install an engine that exceeds the placard HP rating......(if you do, they're not only idiots, but they'll probably do other dangerous "stuff" to your boat!!!)

We live in a world where someone can sue because they spilled hot coffee on themselves...... suing for damages from something like intentionally exceeding known accepted boat safety issue would be a "given"!!





Cheers,



Rick

 

[NSBCraig]

Re: Outboard horsepower debate

Lose your house.... go to jail.... Ha ha ha ha! That's some funny paranoia there friend, it just isn't based on reality though.

 

[HT32BSX115]

Re: Outboard horsepower debate

Lose your house.... go to jail.... Ha ha ha ha! That's some funny paranoia there friend, it just isn't based on reality though.

Hmm... That's a remarkably naive statement (no offense btw!) You must not know anyone this has happened to........ Good friend of mine took his kid and her friend to the lake for a little boating (wake-boarding etc) kids friend falls off the wake-board and gets hurt (not seriously).

Kids friend's parents get a lawyer and sues my friend for "damages". Since the damages were minimal, they settled out of court and the insurance company was able to cover most or all of it.

Now suppose the kid was killed.........can you visualize this thing spiraling out of control? (Lawyers are anywhere from $200-400+per HOUR!) look at your liability policy. Once you reach the policy limits where do you suppose the additional $$$ comes from? (now....add in negligence from violating any laws.....drinking, no observer, exceeding HP limits, or any other "easy-kill" item) THEN do the math..........


Cheers,


Rick

 

[metriccrescentwrench]

Re: Outboard horsepower debate

WOW!!! How did a civil, legitimate conversation about how much engine is needed for pulling a skier turn into a pi$$ing contest about grossly overpowering boats? Talk about egregious thread creep. :facepalm: