Over maxing H.P. rating

[crazy]

Think there would be any harm in putting a 140-150hp motor on a boat rated for 120hp?The boat is 20’6” with .100 gage aluminum hull and .125 gage on the transom. Least that’s what I think it is. They don’t make the boat anymore and when I called the company that produced it the guy in the shop could not remember. But he did say that it would probably hold it. :big_smile:

[Catter]

Might want to check your local laws, if I remember correctly you could get in trouble if they wanted to push the issue. (at least here in Arkansas)

Joe

[FishBrew]

plus why would you want or have to?

[Mark J]

Your boat, your life.
I'm sure maximum horsepower ratings can be exceeded but by how much? Where is the cut off point?

It's not always the horsepower that is the limiting factor, its weight capacity.


Personally I think an aluminum boat is the last boat material I would choose to play with exceeding maximums for various reasons.

[three_rivers]

It would be a risk you are willing to be prepared to take. Going over the hp rating by 10hp or so i've heard of but your talking about 30hp or more. In some states i believe it is against the law. I do know in tourneys the boats hp ratings can't be exceded. Me personally i'd go with whats posted on the boat.

[crazy]

I've thought about the weight issue. The motor that's on the boat now is a 115 yamaha 2 stroke weight 358 pounds. The 140 that I would like to put on it is 410 pounds. From the same company as the 140hp there motor that is 115hp weighs in at 416 pounds. The yamaha 4 stroke 115 is 402 pounds. Either way I'm going to end up putting a 4 stroke motor on the boat and the weight of the motor is going up. Why would I want a bigger motor more displacement and running the same speed now at a lower RPM.

[Bobpaul]

Keep an eye on the upper corners of the transom. You might want to consider reinforcing the transom at the port and starboard contact points to the hull.

Always travel with a motor support.

[riverratmatt]

in some cases max horsepowers are a joke mine forinstance has a max of 40 hp but i dont thing it would be safe with more than 25hp cnsidering its size.
so i would recomend going under the max

[Katmandeux]

This sounds like a Darwin Award in the making.:big_smile:

Okay, not really, but that rating is there for one reason: to keep you alive. At the very least, you owe it to any passengers you might have to be the best, most responsible "captain" possible. Don't do it. Please.

[zappaf19]

In Indiana if you have over powered the boat you get a ticket. Yes they do look at the little plate from time to time.
Bill

[JAYNC]

I totally agree, My boat is rated for a 90 but I have a 75 on it and it does great. Its just like speeding in a car, yeah you might get there 2 minutes faster but is it worth the risk. I would hate to see a boat jump a wave and see the transom break off.

[jim]

Listen to Mark, aluminium is the last thing you want to over stress.More weight,plus vibration ,plus over powered is a recipe for disaster.I am curious why the 4 stroke?There are plenty of 2 strokes that in test after test have proven MORE economical than the 4s at normal operating speeds..Mercurys' OPTIMAX comes to mind.The new 2 strokers are very very good at fuel economy and generally give you a better hole shot and top end.The 2 strokes are particularly economical in the cruising range you seem to prefer.If I were you I would carefully research ALL the engine options.You may be able to get more HP,and still stay within your approved transom weight range.The Coast Guard will flat out ticket you because that is one of the things they DO look at if they inspect you.A 2 stroke 120 would give you a little more HP and with a proper SS prop might boost your performance a little,(Check the RPM range of any engine) and still be in the correct weight range.BASS and WALLEYE BOATS magazine has done many of these tests as has Trailer Boats.Go to their websites and you can read the articles.I would love to have a new Mercury VERADO 200HP but it is close to 100lbs to much for my transom so I have to stick with my Optimax which isn't painful at all.Better that than find the VERADO and transom sitting next to me at the console.:ooooh: :confused2: :tounge_out: :big_smile:

[crazy]

Why the 4 banger. Because I don't like the motor that's on there now. I want a warmer blooded motor. One that likes to start when it's 17 degrees outside. This motor is also hell on fuel. Now yes I can probably play around with prop pitch to find one that is better suited for this boat. As far as the coast guard plate that is on the boat. There is no max weight listed for the motor... just says max HP 120.

This is what it kind of looks like... Although Duracraft has been bought out by another company. So they don't make the boat now. But it is a Duracraft "Cat Master" Looks kind of like there bayboat just better suited for catfishing the rivers.
http://www.duracraftmarine.com/BayBoats.htm

[AwShucks]

Why a four banger... because in some states, think California, the Corp of Engineers won't allow a 2 cylinder motor on the lakes. Bad as it is, if California starts something, the rest of the nation follows.. look at smoking in bars and resturants. Where did it start?

[Phil50]

You might also think about insurance. My State Farm agent says they won't insure a boat that is over-powered.

[SkiMax]

Also, you would probably have to do it yourself. I don't know of any reputable boat mechanic or store that will overpower a boat. So ur going to have to rig it yourself. I would just stick with a smaller motor. I bet that 120 makes u go faster than any of the fish can swim!

[jim]

Understand you don't like whats on there now.For everybodies info there are two strokes that meet the CARB law requirements for California.In fact I think the new E-Tecs have been given a 4 star rating.If your old engine is carbuerated then it is a gas guzzler no question.What I am saying that if you are getting a new engine don't discount 2 strokes because the new generations are just as fuel efficient as 4 strokes and some are more so.Secondly they weight less than 4s.Finally the CG has a data base of boats which you and they can go to that tells ALL the specs on your boat.That boat has a max weight limit for the transom.As far as cold starting the new generation of direct injected 2 strokes fire on the first turn of the key.I have 8 boats here in my Navy boat crew and we use E-tecs and they are the same way first turn of the key.Before you commit to 4s research the new 2s.

[Mark J]

Bobpaul is in the business. He told me some time back to seriously look at the E-Tec before I dropped the money for a 4 stroke.

I've fished with the 4 strokes and love them but I dont own one. I really dont think the verdict is out yet on a 4 stroke. It will cost alot more to rebuild a 4 then a 2. There is alot more moving parts in that 4 stroke too. More parts to fail.

In the situation I would have to have someone SELL me one or the other.
Once the 4 strokes came out strong the 2 strokes got alot better.

[Bubbakat]

Four strokes aren't new to the market. I would opt for the new e-tech and as for over powering that boat if you have an accident and hurt or kill someone you can better bet that someone will measure the boat from tip to stern and tell you what size motor that boat was built to handle.

Its your boat and your desicion but I will try to keep and Eye out to the location you are fishing so I can go some where else because it will be a disaster waiting to happen.

[Bobpaul]

I told him what I told him because he's going to put that motor on there.

I know a guy that overpowered a boat that was only rated for a 6 hp and got it up to 21.5 mph. Now that's an idiot!!!

[Mark J]

Boats are rated for a reason. The rating isn't a guideline.
Sure they have a fudge factor built in but we dont know it is or the condition or the age of the boat for that matter.
If I say well I should be able to go 10 horses over with no problem, then the next guy will go 15 because my 10 might work, then you got the next guy that will go 40 over because he happens to have one laying in the garage.

It aint worth it from numerous standpoints and eventually it will become a problem in some form or other. If you are lucky it will be a cracked transom.
The transom isnt the only part of a boat that takes the brunt of an engine.
Outboards create enormous side to side forces and hull flexing.
Your damage may be contained to the transom where most people will look.
An engine can cause your hull to crack well forward of the transom where most people will least expect.
Its not just a transom that has to be built for the horsepower, the entire hull does. Qualified marine engineers, designers, or marine architects design boats, not motor companies. Some build in rather large safety margins where others have little or none.
Aluminum boats are good boats but they are what they are.

[Willy]

I have had some experience with larger motors on boats and it is a hassle getting them rigged right. My advise is to get a good price on either a 115 optimax or a etech and go from there. The only boats I am aware of that you can put about what ya want on them is Clark boats as they are commercial rated and ya pay for that. Very few boats made now are built to handle alot of stress on the transom with over the hp rating. You will find in time the transom will start flexing and you do not want that. I had a 1860 Ultra Jon with a 90 Merc on the back and it was rated for a 80hp motor and when I sold it the transom was getting weak and needed some work. I know of a good Mercury dealer that ya can call if ya want and he is good to deal with. Also the bunch at Smithville Marine might be able to help ya also.The guy that you looked at his boat that he won at the classic runs a Etech and loves it. I have ran Mercs for a long time and after being around the new Etechs I am gonna look hard at them on my next boat. Only one boat that I want is gonna be a Lund and gonna have to see what motor option is the best deal when the time comes.There is a new Lund gonna be out that will be the nuts for cat fishing and I think smithville is gonna have one this spring at their open house.

[bootshowl]

Are you guys fishing or water scootin or racing or something? Why would you want yer hat to blow off while yer trying to fish? I don't really understand the need for speed if you are fishing. That's why God came up with the motorcycle.....Ron White said he didn't know a bass could swim 6o MPH.....Man I couldn't agree more. I seen it on TV, the tournement fishing. They stop and say "Lets try (insert location)." Then you cut to the helo view, with the boat flying across the water like Crocket an Tubbs making a coke drop for the bad guys.....maybe I'm just getting old. I don't push my harley much over 100 anymore....but I ain't fishing either. Just strange if ya ask me, and if ya run that way, I'll just stay in my little boat thanks anyway. Have a great wind burn.
:big_smile:

[StuBone278]

Sounds like a bad idea. I also don't think 20-30 horsepower will really make a huge difference in the speed when its already at 100 horses to begin with, it mainly has to do with the hull of the boat. The larger motor will also just burn more gas. I would just play it safe and stay under the limit.

[fat_fish55]

i was kinda wondering the same thing
i have a 16 ft flat jon boat and dont know the max hp.
it has a 10 and was thinking about putting a 40 on it from my other old deep v
i was thinking it would be fine especialy if i didnt run it wide open?

[bootshowl]

I really was asking an honest question. What is the advantage of having a fishing boat that has H.P out the wazoo. I've ask several salesman, and get that blank stare, like, uh-oh, this guy don't get it. Back in the day it was common to see fishing boats with 5 to 25 HP motors and guys seemed happy. Now I see the basically same size boats with motors large enough to give you pause....excuse me, but isn't that the same motor thats on that 20 some foot pontoon over there? For ocean waters I can understand. But for freshwater, what gives? What's the up side to all the power? How does it help your fishing?
:confused2:

[crazy]

I have no problem with speed. Besides you said Boots that you hardly go over 100 anymore. Sounds to me you don't mind it either. As far as the Etech go I hear it's not as clamed so I'm not going to get one of them. That’s talking to either people sponsored by them and others. I'm leaning towards getting a Suzuki 4 stroke. Everyone I have talked to that owns and runs one really likes the motor. Then again I don't even own this boat yet. The boat is built like a rock and is only a little over a year old. We will see in that department. Still trying to decide if buying the boat and then getting a new motor for it is cost effective. Other then just spending the money on a brand new boat/motor combo. Oh yeah someone mentioned before that there has to be a max weight for the motor. Well there's not so what ever that means. I know because I looked real hard for it.

[Willy]

Most boats will have a horse power rating on the plate on the transom and it will state the max weight the boat will handle or the max number of people in the boat. No where will it state the weight of the motor but a common rule you should go by is get the most hp to weight factor you can. Too big of a motor will not perform right as it will try to drive the front of the boat into the water and nothing you can do will help that.I have seen a bunch of boats that size with the 140 motors around but most are not the best about fuel used or performance. There used to be a boat up this way that had twin 60 Mercs on the back and it was a case of more money than brains as it would not run any faster than one with a properly set up single motor.As far as speed I have been in several that would scream but ya gotta lok at how they perform also.One is a death trap as it is a 17 ft v hull with a 90 2 stroker and it is a handfull to operate.Hull design plays a big part in how the motor performs and where you fish the most will also be a deciding factor in what hull you need. I have had a true flat bottom and also a newer performance type semi v style hull and each had its owm drawbacks. Just gotta see what you need the most. if all I was gonna do was fish the river a good 20 ft jon would be all I need but I want a v bottom so I can handle the waves and wakes better on bigger bodies of water. It will have a windshield also as momma doesnt like getting wet as much now as in the past and the ride is alot smoother on rough water if you gotta run long distances fishing tournaments. The older I get the more I want the creature comforts that are available now to make it more enjoyable to fish in bad weather and the more comfortable the seats the longer you can stand setting waiting on the fish to bite.Look around at what is available this year at the sport shows and there is deals out there just gotta find them.

[fishhook]

I just bought a boat off of ebay and drove to Dallas, Tx. to get it because it was what I had been looking for at about half the cost of what its worth. Its a modified-V flat bottom center consol aluminum Sea Ark 24' long by 8' wide and it has a 140hp suzuki mounted on it and it only runs about 8 mh faster then my 17' Invader center consol fiberglass boat with a 90hp Johnson on it. This boat is classified commerial with no hp or weight limit, although if you go to the Sea Ark site on the internet it gives a weight limit of 2065lbs but no hp limit. Here in Ohio all boats that are not commerial has to have a hp and weight limit plate and a lot of the lakes here you will get your boat inspected by the DNR before you can launch. I thought that plate was a coast guard rule covered in my boating course years ago but I could be wrong, my memory isn't as good as it used to be.

[Bobpaul]

I really was asking an honest question. What is the advantage of having a fishing boat that has H.P out the wazoo. I've ask several salesman, and get that blank stare, like, uh-oh, this guy don't get it. Back in the day it was common to see fishing boats with 5 to 25 HP motors and guys seemed happy. Now I see the basically same size boats with motors large enough to give you pause....excuse me, but isn't that the same motor thats on that 20 some foot pontoon over there? For ocean waters I can understand. But for freshwater, what gives? What's the up side to all the power? How does it help your fishing?
:confused2:

There's nothing about HP that helps your fishing, unless your a tournament fisher and time is important.

It's all about the same way you feel about you bike. Why not just ride a moped?

[bootshowl]

Thanks Bob. Don't know why it was so hard to get someone to answer that one. I ask at two marine dealers, and they said more was better, when I ask why, got the "uh-oh" stare. At bass pro ask twice and didn't get any answer at all....boating has been harder to get a good understanding of than any other recreation I've tried to further my knowledge of. If you are not knowledgeable about something, you usually start by asking simple questions.
:smile2:
Some days a moped would be fine....

[trnsmsn]

[quote=crazy;501007]I have no problem with speed. Besides you said Boots that you hardly go over 100 anymore. Sounds to me you don't mind it either. As far as the Etech go I hear it's not as clamed so I'm not going to get one of them. That’s talking to either people sponsored by them and others. I'm leaning towards getting a Suzuki 4 stroke.

I'm not saying any of the other engines are inferior but I own a 4 stroke 70hp Suzuki & LOVE IT. It's dependable a very fuel efficient. With the electronic fuel injection it starts on the firsy crank every time, no matter what the ambeint temperature happens to be !!

[Mark J]

Some of the Bassmaster classics have been won by making a 100 mile run including locking.
Those boats are fast. Faster then one just like it you buy at the dealership.
When Ranger supplied the boats there was a team that built and rigged the 50 boats a year supplied to the tournament. The set up on them was phenominal.

The setup you run on any new boat you buy is only as good as those setting it up. Most are never water tested before you drag it home.
There is alot you can do to a boat to make it run better.

Depending on the hull you could replace a 100 hp motor with a 150 hp motor and only gain 5 mph in speed or go from a 150 to a 250 and gain 9mph.
Its a case alot of times of how much fuel you are willing to buy.

In my case I'm constantly looking at designs and materials that offer larger boats with smaller engine requirements and taking no hit in performance.
There are plenty out there too. but you have to be the builder.
These boat manufacturers are in bed with the engine manufacturers too far for them to start logically building boats. They already have the public snowed into thinking you have to have a big motor for a big boat, the heavier a boat is the better it rides, and spending 600 dollars on a prop that will get them 3 more MPH.
I'll make a living at disproving them one day.

[Bobpaul]

Mark, you nailed it.

Boat hull efficiency is a huge factor in performance, then proper setup.

Those that have seen my 1670 Laguna aluminum with the jack plate I built just to accomidate a 25 hp 87' Merc might remember the speed I got out of that boat. It's not fantasticly fast, but 32 mph with only a 25 hp engine on a fully loaded boat with two men, ain't too bad.

The boat's only rated for a 35 hp.

[Mark J]

Bob, yea, those bass boats everyone hates are designed from the keel to the waterline for speed. They suck at slow speeds like trolling.

You have to give up something somewhere in any boat you buy.
You can put a 300 horsepower motor on a brick and not accomplish what a 5 horse would do.

[cook]

I'm even below a novice when it comes to boats and motors,but I do have a couple thoughts.
1) seems weight,stress,and vibration play as important part ,more than actual H.P. besides is a 115 motor really 115....any chance the manafacturer might be measuring it under lab conditions.Naw....they would never do that to promote their product:big_smile: :big_smile: :big_smile:

2)2 stroke vs. 4 stroke..this might be apples to oranges...but...autos have been around for over 100 years,don't see many 2 stroke fords or chevys on the road these days:roll_eyes:

[Mark J]

Jon, your car isnt turning 5500 RPM's at 35 MPH either:big_smile:

[WylieCat]

The Coast Guard has a formula, (2 X L X W) -90 = rated horsepower, that they use for computing the horsepower rating. Typically the manufacturers will rate the boat at about 80%-85% of this number and this is what is on the plate.

Technically, there is no Coast Guard regulation prohibiting running a larger motor, but there may be state and local laws that prohibit it. Furthermore, it may or may not affect your insurance.

The biggest concern would be if you are ever in an accident, even if it is not your fault. The fact that you were running a motor larger than it is rated for would put you "further along in time" than you would have been were you running the suggested size. It's a bunch of technical legal mumbo-jumbo that basically means "contributory negligence", in other words it is partly your fault.

[cook]

Jon, your car isnt turning 5500 RPM's at 35 MPH either:big_smile:
You never rode with my daughter!!:big_smile: :big_smile: :big_smile:

[Katmandeux]

It's probably a mistake, but both of the boats on the Duracraft link posted by Crazy are rated for 120hp, even though there is a substantial difference in the L/W of the two.

The boat's a bomber, btw.:smile2:

[crazy]

It's probably a mistake, but both of the boats on the Duracraft link posted by Crazy are rated for 120hp, even though there is a substantial difference in the L/W of the two.

The boat's a bomber, btw.:smile2:

I don't think it's a mistake. I think they play it the safe way. Even if you figure it by (2xLxW)-90 You get over 150hp. Then you take into account that the US cost guard plate is for boats under 20 feet and this boat being 20' 6". But hey lots of information came out of this thread. One nice link I did find is this one.

http://www.uscg.mil/d8/mso/louisville/WebStuff/comdtpubp16761_3b.pdf