MFG Carefree Transom?!

[Chrisravosa36]

13'6" Runabout 50hp Overpower?

Hi, Im planning on putting the 1974 johnson 50hp on the back of the 73' MFG Carefree. Its legal in my state, but I want to make sure its safe. Its rated max.30hp. The years before this were all rated for 40hp, but when MFG sold its company over to cresiliner, they wanted to make it down to 30hp. It is the same hull, same format. THe only diffrent things about it are the decals and pin stripes. I was planning on putting a 40hp on it, but I got this Johnson for next to nothing, and wanted to try it out. Anyways Il have quite a bit of gear on the boat to add some weight, max weight is 900 something, cant quite read the label, but it starts with a 9.

Myself - 160lbs
Motor - 187lbs
Marine Deep Cycle - 70lbs
Starting Battey - 40lbs
Seats - 15lbs
Gas 6 Gallons + Tank (Plastic) -40lbs
Safety Gear - 20lbs
Fishing Rods/Bait - 30lbs
Trolling Motor - 27lbs
All Wiring, Lights and accessories - 20lbs
Carpet - 8lbs
Steering system - 15lbs
Throttle - 5lbs
Ignition Switch + Wiring - 2lbs

TOTAL WIGHT IN BOAT = 639LBS

So I still have plenty of weight for one more adult.

My idea is to keep the batteries in the front, and gas in the back. This should help balance the boat better, any input on this? Ofcourse I will have to test it to ind out the best solution. I will definitely be using a 4 bladed propeller, I hear it is better for turns and just handling in general. Anyways, the motor is older, I hear that they use to measure them at the powerhead for 50hp back then, so by the time the power got to the water, it was around 45 - 48hp. I am working on the transom, it will defiantly be strong enough, as it will be seacasted. I would have got a 40hp, but I really want to try out this motor, my orignial plan was a 40hp, but I got the Johnson seized up for 50$, and am fixing her up, so if it doesn't work out with the 50hp or its just to dangerous, I will just buy a 50hp. Safety is KEY! All imput is valued greatly, I know it is not a great idea to overpower, but I think this would be safe with the proper setup. Ofcouse I wont be hammering the throttle, as I am a fisherman and will constantly cruise at 3/4. *It is a soft Chine Hull, rounded bottom with a long bad.

 

[flyingscott]

The coast guard makes the rules and it doesn't matter the only motor they consider legal for that boat is a 30. How the motor was rated means nothing when it comes to the rating on the boat. Another thing to remember is if somebody gets hurt you are on the hook for all liability.

 

[boobie]

Agree with the above !!! Especially with the getting hurt part.

 

[jbcurt00]

Hi, Im planning on putting the 1974 johnson 50hp on the back................
(of a boat rated for a 30hp)
...............Safety is KEY! All imput is valued greatly

Mutually exclusive statements,

......
I know it is not a great idea to overpower.......

Then why keep asking?

Havent you asked this already and gotten similar replies suggesting you not proceed w overpowering your MFG?

 

[Chrisravosa36]

The coast guard makes the rules and it doesn't matter the only motor they consider legal for that boat is a 30. How the motor was rated means nothing when it comes to the rating on the boat. Another thing to remember is if somebody gets hurt you are on the hook for all liability.

Total agree with you, but the coast guard never rated this boat, it was rated by the manufacture itself, it does not have the modern yellow plates. Its basically rated 40hp physically, but in terms of the manufactor its rated 30. Im on the hook anyways if I put a 30hp on it, im not going to beat her to death and scream across thee water at 40mph. Just asking if this is a little to much H.P. I took my states saftey coarse, Im care when I boat. Even if it was a problem with the coast gaurd, I boat on a lake, and this lake has close to knowbody on it.

 

[Chrisravosa36]

Mutually exclusive statements,



Then why keep asking?

Havent you asked this already and gotten similar replies suggesting you not proceed w overpowering your MFG?

I have asked it in my other fourm when I first got the boat, Ive learned much more information about the boat, and the motor, I thought id ask it again in its own post. Overpowering is never safe, like I said. But im not sure if the weight, prop and motors ability is produce less than 50hp, im guessings its accutally 45hp down at the prop. So essentiayl 5hp overpowered.

 

[jbcurt00]

So basically you're just asking for permission to do what you plan to do?

Estimate, figure and guess all you like, its still overpowered and you know its not a good idea.

 

[Chrisravosa36]

So basically you're just asking for permission to do what you plan to do?

Estimate, figure and guess all you like, its still overpowered and you know its not a good idea.

Not asking permission, Im asking for advice, thinks that would make it more safe, such as trim tabs, more weight ect.

 

[ondarvr]

The CG does not make the rules, they make a recommendation that this should be the max HP for the hull. The CG doesn't enforce anything that has to do with putting a larger motor on the boat. Some states use the recommended rating as the max allowed, others don't and have no rules about it. Also, insurance companies will still insure it and pay claims, they might ask you what HP you have on it, others don't, they all still pay.

I'm not saying to do it, just getting the info corrected.

 

[GA_Boater]

Total agree with you, but the coast guard never rated this boat, it was rated by the manufacture itself, it does not have the modern yellow plates. Its basically rated 40hp physically, but in terms of the manufactor its rated 30. Im on the hook anyways if I put a 30hp on it, im not going to beat her to death and scream across thee water at 40mph. Just asking if this is a little to much H.P. I took my states saftey coarse, Im care when I boat. Even if it was a problem with the coast gaurd, I boat on a lake, and this lake has close to knowbody on it.

Yes, the USCG did rate the boat. How did they they do it? Simple, the CG has a formula for rating max horsepower. All manufacturers must follow this formula and the results of the formula is on the capacity plate, whether it's a yellow, green or purple plate. Your 1974 boat was rated following the USCG rules in effect on the date of manufacture. The CG has been around a long, long time, don't forget.

Boat manufacturers don't make this stuff up. The max legal horsepower is what's on the plate, in this case 30 ponies. It also doesn't matter if the HP is powerhead or prop rated, as so many like to pick nits over.

So the USCG did rate the boat via the manufacturers compliance with this USCG rule and a myriad of other rules. Failure to adhere to all of these rules hurts their pocketbook unless an exemption has asked been for and granted by the USCG.

 

[Chrisravosa36]

Yes, the USCG did rate the boat. How did they they do it? Simple, the CG has a formula for rating max horsepower. All manufacturers must follow this formula and the results of the formula is on the capacity plate, whether it's a yellow, green or purple plate. Your 1974 boat was rated following the USCG rules in effect on the date of manufacture. The CG has been around a long, long time, don't forget.

Boat manufacturers don't make this stuff up. The max legal horsepower is what's on the plate, in this case 30 ponies. It also doesn't matter if the HP is powerhead or prop rated, as so many like to pick nits over.

So the USCG did rate the boat via the manufacturers compliance with this USCG rule and a myriad of other rules. Failure to adhere to all of these rules hurts their pocketbook unless an exemption has asked been for and granted by the USCG.

Your right, they did. I just looked at my plate again. But even rated at 30hp, I can put a 50hp on it right? Thats what ondarvr stated. I understand your reasoning. I relize overpowering is not a great idea, I just want to try it first, see if it preforms good and if not I can throw a 9.9 on the boat till I can afford a 30.

 

[jbcurt00]

Thats not what Ondarvr said.

He presented facts

Might want to take a look at the MA boat law pamphlet and check your facts. Overpowering is covered.

Plainly, and simply.
http://www.google.com/url?sa=t&sour...5XktRdbHAY-O_LSdQ&sig2=2qpVnnrEiiKZlijP-_rfTQ

 

[GA_Boater]

Do what ever you want. Why bother asking if you were putting the 50 on any way. Once you put it on, you won't be taking off unless you have issues.

ondarvr did not say you can put the 50 on. He said "I'm not saying to do it, just getting the info corrected."

 

[Scott Danforth]

no one on this forum will ever recommend overpowering.

here is the forumla for calculating the hull hp. http://newboatbuilders.com/pages/hp.html

please note that this is CFR 33 sub part D, 183.51 - 183.53. CFR is Code of Federal Regulations.

BTW, your weight and all the weight of stuff including motor must come in under 900#, however it has nothing to do with the torque applied to the transom due to the force of the motors power pushing the prop. The max hp portion covers this.

 

[Chrisravosa36]

BTW, your weight and all the weight of stuff including motor must come in under 900#, however it has nothing to do with the torque applied to the transom due to the force of the motors power pushing the prop. The max hp portion covers this.

So even with the transom redone, it still can damage the boat somehow? I shoud have really never asked this question in the fist place, Im just looking for some feedback for ways to improve the stability and handling, but I guess I will figure that out after I run it.

 

[ondarvr]

The calculations are designed to get a safe idea of what the HP should be without doing any on the water testing of the hull, it has nothing to do with how strong the transom or hull was built. Most transoms far exceed the strength needed for the rated HP of the hull, so from that angle overpowering a little wouldn't be an issue. The problem is the hull design, without testing there is no easy way to tell how the hull will respond to more HP, it may work fine, or it could get scary quickly.

Just learning how to drive a boat at high speed can take some practice, there can be some real pucker situations where you might find religion during the process. And this is on boats that are built and designed to go that fast. Take a small light hull that probably was designed late at night on napkin by some guys with too much to drink and you don't know what's going to happen when more HP is mounted on the back.

 

[Chrisravosa36]

The calculations are designed to get a safe idea of what the HP should be without doing any on the water testing of the hull, it has nothing to do with how strong the transom or hull was built. Most transoms far exceed the strength needed for the rated HP of the hull, so from that angle overpowering a little wouldn't be an issue. The problem is the hull design, without testing there is no easy way to tell how the hull will respond to more HP, it may work fine, or it could get scary quickly.

Just learning how to drive a boat at high speed can take some practice, there can be some real pucker situations where you might find religion during the process. And this is on boats that are built and designed to go that fast. Take a small light hull that probably was designed late at night on napkin by some guys with too much to drink and you don't know what's going to happen when more HP is mounted on the back.

This hull is around 400lbs, so its not a napkin to say. But it light, alltogether its around 1000lbs. I understand that driving at high speeds can be risky and dangerous. Ive experinsed it with my jon boat, I had a 9.9hp on it, not gear in it and I was going 27mph. At that point the slightest turn would probally wreck.

 

[ondarvr]

The late at night on a napkin comment comes from this.

In the early days of fiberglass boat building there were hundreds of small shops all around the country building boats of all shapes and sizes, there was very little if any professional design or input going into what was built. Most of the designs were dreamed up in some guys head and while they were drinking one night in a bar with his buddies (which was common practice at the time, much of the time they would drink all day too) he would sketch out a new design on a napkin. The next day they would start building the tooling for that boat, it would get built and sold with not much fine tuning of the design, some worked, some didn't.

 

[JimS123]

But even rated at 30hp, I can put a 50hp on it right? .....I relize overpowering is not a great idea, I just want to try it first, see if it preforms good and if not I can throw a 9.9 on the boat till I can afford a 30.

You got your answer, and for once it was unanimous,.....LOL. You were outvoted 20 to zero.

Its quite obvious you have never taken a boating safety course. You sound very inexperienced besides.

Just do us all a favor, please.......Take a picture of your rig and post it, and then tell us where you live, so we can all be on the lookout for you and stay the heck out of your way. The problem with irresposibility is that the person that gets hurt was usually just an innocent bystander.

 

[64osby]

Offer the 50 HP motor up on CL, for sale or trade for a 30 HP motor. Trade or sell and buy.

Solves many problems and might put a little money in your pocket.

Run its with the 9.9 in the mean time.

My .05