queensland Can you increase a boats maximum horsepower?

[ggg]

Hi all,

I am just wanting to know the process in changing a boats maximum horsepower and it’s cost?I only want to see if I can improve the maximum by 10hp. 

[Brodie_S]

14 minutes ago, Jaz44 said:

Hi all,

I am just wanting to know the process in changing a boats maximum horsepower and it’s cost?I only want to see if I can improve the maximum by 10hp. 

Buy a outboard thats higher by 10HP then you’re current one . No need to thank me

[Do$tylz]

Jaz44 - depending on your outboard, there may be some things available to you to increase its HP.

I have a Merc SeaPro 25, but by changing a flange thingy (so technical) on the carby, it takes it up to 30hp. Not saying that's a valid thing for your outboard, but there may be a small hack as well.

[Brodie_S]

20 minutes ago, Jaz44 said:

Hi all,

I am just wanting to know the process in changing a boats maximum horsepower and it’s cost?I only want to see if I can improve the maximum by 10hp. 

Lol sorry couldn’t help myself. Ok there a few ways I’ve heard of that increase HP of outboards but the most common one I can think of is . Swapping out the propellers with something that is a itch less in pitch . Wait do you have a outboard or a inboard 

[Kenne]

There is a video on Brisbane Yamaha How to turn a 50hp into a 60 

[benno573]

1 hour ago, Breaming with bro said:

Lol sorry couldn’t help myself. Ok there a few ways I’ve heard of that increase HP of outboards but the most common one I can think of is . Swapping out the propellers with something that is a itch less in pitch . Wait do you have a outboard or a inboard 

I am fairly sure the question was around how to change the max HP rating for a hull as opposed to how to increase te HP of an outboard.

I don't believe there is a way to modify a hull to increase its max HP rating.  Unlike increasing the GVM of a car, it is not as simple as changing/upgrading components, it is all to do wih the weight of the engine, strengh of the hull etc.  lots of people put an outboard on that is over the max HP, this leads to huge issues with insurance and those sort of things and is not recommended.

what kind of boat / outboard combo are we dealing with here @Jaz44 and what are you hoping to achieve?

[ggg]

It’s a Quintrex 420 Dory Widebody. It’s max is a 40hp, but I want to put a 50hp as there is a cheap E-Tec that’s only a few years old in my area. 

[benno573]

ah ok.  unfortunately I don't believe there is a "legal" way of doing this mate.  While I'm sure the hull could handle it, but you wouldn't be able to get insurance and if you were pulled over by the water police, depending on the state you live in (thinking WA based on the rankin in your profile pic?) there are fines and the like associated with having a not "waterworthy" vessel.

[The Mad Hughesy]

paint it red? might make it go faster

is the max HP rating of a hull determined by the weight of the engine? or are there other factors. im curious as my hull is rated to 90hp

[ggg]

I live in QLD. I can’t just change the builders plate and get the boat checked by a marine surveyor?

[The Mad Hughesy]

just give a local boat builder or seller a call, im sure they would know

[Do$tylz]

2 hours ago, benno573 said:

I am fairly sure the question was around how to change the max HP rating for a hull as opposed to how to increase te HP of an outboard.

I don't believe there is a way to modify a hull to increase its max HP rating.  Unlike increasing the GVM of a car, it is not as simple as changing/upgrading components, it is all to do wih the weight of the engine, strengh of the hull etc.  lots of people put an outboard on that is over the max HP, this leads to huge issues with insurance and those sort of things and is not recommended.

what kind of boat / outboard combo are we dealing with here @Jaz44 and what are you hoping to achieve?

Good pickup benno. I totally misunderstood the question too.

[benno573]

2 hours ago, Jaz44 said:

I live in QLD. I can’t just change the builders plate and get the boat checked by a marine surveyor?

I wouldn't think this would be legal mate... give a boat builder a call and check for options but my understanding is that tampering with the hull label is not on.

[Nog]

A mate got his Seajay 4.3 re-rated from a 50 to a 60 by  a marine surveyor, no  probs

[ggg]

Thanks Nog. I made a few phone calls and it can be done. How did he go with insurance?

[Ed.]

If you have a hull that is rated higher than the current outboard HP on your boat currently then it isn't a problem. If you are already at the max dictated by the recommended Max HP of your boat, then whilst physically you can put on a larger motor but you then will run foul of the insurance companies  and most likely the water police as well. It's a bit like  putting in a high HP V6 motor into a car that was designed for a 4 cylinder motor.

Whist it can be done (hot rods spring to mind) there will be lots of hoops, conditions and modifications  to go through and it may be easier and better to just trade it in on anther boat that is more adequate. A small increase in HP may not be a big issue but if for example you were to try and put a 120HP out board on a boat designed to only hold a 40HP motor I would imagine the effort would not be worth it if even it was allowed at all.

If your boat had a very old 40HP on it then changing it to a much newer 40HP would most likely show a big improvement in performance.

A boat's max HP on the transom is worked out by the boats flotation, strength of the fiberglass/ boat material, length and shape and other design factors.

[ggg]

Okay. All I want to do is change the max outboard by 10hp. I have had some people tell me they haven’t had any dramas with insurance but I don’t know. I might just have to ring the insurance company. 

[Kenne]

12 minutes ago, Jaz44 said:

Okay. All I want to do is change the max outboard by 10hp. I have had some people tell me they haven’t had any dramas with insurance but I don’t know. I might just have to ring the insurance company

Insurance companies will tell you any thing to get your money  Then you need a lawyers degree to understand there 500 page fine print  You never know how good an insurance policy is to you try to claim  

[Another Wazza]

Hi Jaz, how old is the 40 that’s on it now?

[AUS-BNE-FISHO]

Hey Jaz44

I doubt you'd be able to do this. Sure, hoons out way bigger engines on their boats. But they're hoons for a reason. I reckon the safety rating would probably be the max unfortunately. 

Paint a 50HP like a 40HP? Then no one will know the difference?  

Cheers Hamish

[Old Scaley]

Why not ring your local Quintrex dealer and ask them if they know if it can happen. I am sure someone will have tried it and they might know how it went.

[ggg]

Already rang Quintrex and they told me it can be done, but I can’t be insured. The engineering company told me otherwise. The motor is a 2005 40hp. There is nothing wrong with the motor, it just seems that 50hp motors are cheaper than 40hp ones in my area. 

[Bood]

I looked into it recently and was told by local boat builder to go to a marine surveyor first and discuss options..

 

 

 

my other thought is buy a builders plate off eBay for small fee and get mr minit to engrave so it looks legit

[AndrewF]

I’m looking to replace my verado 275 with the new lighter 350. But my boat only rated for 275, because that’s the largest engine there was when it was built in 2007. There are similar Hulls with larger engines, is it possible to get it changed. Thanks

[Bob9863]

Not saying I've ever done this but hypothetically say I had an 8hp Evinrude on an 11ft tinnie and didn't want to have to register it. 

A hypothetical fix would be to get a, sign writer to change the 8hp to a 5hp, and that hypothetical boat wouldn't need to be registered. 

If it was a 2nd hand motor then hypothetically you would have bought it as a 40hp.