Too much HP?

[bleblanc]

If you run an outboard that is more HP than the boat is rated for, Does it actually do damage to the hull/transom? I'm refering to a 130hp Merc on a 17' Aquasport...<br />Thanks,

 

[Boomyal]

Re: Too much HP?

At very minimum you could have a safety/stability problem. The physical structure may or may not handle the extra load. That would probably be the least of my concerns.

 

[cobra 3.0]

Re: Too much HP?

sski2ski, what hp is the boat rated for?

 

[bleblanc]

Re: Too much HP?

Boomyal,<br />So, you would be mostly concerned about the safety/stablility or are you refering to the insurance issues. I think (The HID plate has been removed) that the boat is rated for 120hp.<br /><br />Thanks for the opinion,

 

[ZmOz]

Re: Too much HP?

It depends on the design and condition of the boat. Usually this forum will allways say to NEVER go above the rating, but I don't agree with that at all. When the rating is made they just use a calculation based on the dimensions and weight of the boat, or something like that, I don't remember, but it doesn't really have anything to do with how well the boat handles at speed or how strong the transom is. My boat, for example, is a Glastron CV-16 rated for 120hp max. I have a 150hp on there and it's been there for 30 years. No problems what-so-ever...except the motor is dead because I forgot the oil. The majority of other owners of the same boat that I have talked to have 135 or 150hp. It only does 50mph with 150hp, and it is a SPEED boat. I can't imagine what you would do with 120hp or less, wouldn't be good for skiing, wouldn't be a speed boat, wouldn't be a fishing boat...<br /><br />Anyway...if your boat is strong and you don't go WAAAY over the rating, you should be fine, other than insurance reasons. If you're worried about that use the cowling from a smaller engine. I strongly recommend you ask this question at http://screamandfly.com/ , and see what they have to say about it.

 

[bleblanc]

Re: Too much HP?

Zmoz,<br />Thanks, man! Great Information!<br />I understand these old Aquasports were built pretty well and we're only talking about 10Hp diff. As for insurance... Maybe that's why they removed the HID plate. <br /><br />Thanks a bunch,

 

[Boomyal]

Re: Too much HP?

You did not mention the estimated rating b4. I don't think I would be concerned with less than 10% overpower. If the boat was only rated for 100 hp then you would possibly have to consider the weight of the 130 hp, the force of additional power on the structure and then of course the stability of the craft at additional speeds that the extra horsepower may cause. I think you would have to have a pretty gross overpower b4 insurance would become in issue.

 

[aspeck]

Re: Too much HP?

ski2sea,<br /><br />I posted the following on another thread about hp, this may be helpful to you:<br />

For the record, the 200hp was a joke! Insurance would have fun with that. However, I got a deal on an 88SPL and over rated mine by 3hp. Insurance agent said that would not be a prob - hope I never have to find out.<br /><br />With that said, my boat is a 16 foot Skeeter. Started out wiht a 70 on it. Was not happy - with one other person in the boat it would not come on plane. Trim Tabs helped some, but too much back end weight. Prop pitch helped some, but still not satisfactory performance. The 88spl did the trick. I was amazed at the difference 18 HP made - top end about 9 more mph and my hole shot increased dramatically. No more fighting to get on plane!

I think ZmOz has the right idea here (except for the part about forgetting the oil!)

 

[crazy charlie]

Re: Too much HP?

Dont worry about the HP.I have a 17ft Mako with a 115 evinrude which is essentially the same motor as the 140 evinrude.No problems and it is fast as heck.I dont think I have full throttled it in 2 years.Charlie

 

[bleblanc]

Re: Too much HP?

Ok... You guys have convinced me that I needn't be worried of structural damage of such a small % of overpower. You guys ROCK! and thanks for all of the information and opinions. <br /><br />THANKS

 

[LubeDude]

Re: Too much HP?

Some of us have been known to ( CHINE WALK )!!

 

[wilkin250r]

Re: Too much HP?

The American Boat and Yacht Council used to have an article on their website titled "How Much Power is Too Much?" <br /><br />The summary of the article is that the HP rating is given by (2*length*width)-90, in conjuction with a "Quick Turn Test" You must be able to turn the wheel 180 degrees, at full speed with the maximum HP motor without loss of control or ejecting the driver. If the boat cannot successfully execute the quick-turn test, then the HP rating was decreased.<br /><br />However, I've also found information that indicates the HP rating of a boat is based exclusively on wieght in such a way that the boat will not sink if it gets swamped. To me, this seems absolutly absurd, since the new 4-strokes are much heavier than the old 2-strokes. It shouldn't have a HP rating, but rather a wieght rating.<br /><br />I think this is a link to the old ABYC article.<br /><br /> http://216.109.117.135/search/cache...es/ABYC%20News/how_much_power_is_too_much.htm

 

[rodbolt]

Re: Too much HP?

Hello<br /> I gotta agree with wilkin. the ratings are absurd and usually have nothing to do with safety. the 2.0 and 2.5 mercs are the lightest for the HP of all the v6's some by almost 200 pounds. my 115 yam on my 15 ft monark mcfast is slightly over rated but its a thrilling ride. other than some porposing problems at 2800 rpm and the fact it takes 4 ft of water to plane when you nail the throttle I have never had a problem with it. other than that at speeds over 60 mph the steeering cable has a tendancy to lock up. I dont think the rating method has kept up with hull and engine technology<br /><br /> good luck and keep posting

 

[sorrydog]

Re: Too much HP?

I would have like to have seen that test done on an Allison basser.<br /><br />Eject! Eject! Eject!

 

[rodbolt]

Re: Too much HP?

hahaha I would love to see a 180 test on a 19 ft carolina skiff with a 100 hp. talk about a skipping stone. an easy way to beat the wheel at 180 is to increase the number of turns lock to lock.<br /> the ABYC rules stated the wheel turning 180 not the boat. I have been in a 24 skiff with a 150 jonnyrude jet drive that in a mostly straight line at 5700 was way to fast and the wind would blow the bow around, no such thing as any turns at speed. you could turn the helm and the boat would pivot on its axis but the direction of travel would remain the same.<br />Like I said. the HP rules are useless and out of date, they are still based on stuff from the 30's

 

[walleyehed]

Re: Too much HP?

I'm with sorrydog.....think Allison rated there boats accordingly??? or any other performance boat for that matter....I think not.<br />Heck, at WFO in my 18ft starcraft w/115 jonny, I'd be in trouble turning the wheel 180 degs....that would be the "posi-ject" method of boat control.

 

[envy83]

Re: Too much HP?

I'm still trying to figure it out. I watch those 250hp rated Bass Boats all day, and I know there is absolutely no way those things could make a 180 at speed.

 

[Skiff_Meister]

Re: Too much HP?

I need some help on this matter as well.<br />I live in Texas but purchased my used 1989 19ft Carolina Skiff in Florida. The HID plate has beed removed. The boat came with a 65HP Suzuki which is a bit rough running. I have a 140 Johnson that I am considering buying but have no idea about the weight difference and HP requirements for the Skiff. Anybody have any suggestions?

 

[walleyehed]

Re: Too much HP?

If the 140 is the looper version, it's considerably heavier by ALOT!<br />If it's a crossflow, it's just "considerably" heavier.

 

[Skiff_Meister]

Re: Too much HP?

How could I tell if it is a Looper version? What is your defination of "Considerably"?<br />Do you think this is a bad way to go?<br />Any ideas on HP rating on 19 ft. Carolina skiff?<br />Thanks for the input!