My plate says 25hp, but I want a 30.

[mini696]

The comp plate on my boat says it is rated to 25hp, but I want to put on a 30hp. The difference in price is not woth worrying about, and they weigh the same. I like to run the engine with as few revs as possible, so the 30 will be my best choice if I am allowed to fit it.

I am wondering if it is legal to fit the 30 to my boat.

I have heard that you dont have to have the comp plate on the hull (especially if it is an onlder hull) is this true? Can I take it off and fit the 30 without harming my insurance etc?

[Noelm]

probably yes and no to most of those questions, best bet is to call your insurance people and let them make the decision, and get it on your policy, you could explain about it being basicaly the same motor and so on, but best of luck, I have heard of people ringing the manufacturers and getting a new rating if it is reasonable, but never done it myself.

[oldie]

Insurance is the biggest concern, you can put a 100hp if you dont insure it, but when it comes to damage from bigger horsepower or accident just like a motor vehicle the one that has over max HP will be responsible im sure!
Id throw a Yamaha CV 30 on the back then rip the 30hp sticker off, both the 25 and 30cv are identicle, but hey im young and reckless!! haha
good luck, i have same prob on my little creek boat says its only rated to 5hp, i see other 11ft tinnies with 15-25hp, im worried about cracking the back end
Oldie

[Wahoo]

Off topic a bit ( sorry Mini )

if your plate says max hp is 250, and the max weight on the plate say 270kg............


now if i was to put a 250hp and it weighed in say at 300kg, what do you do here?


Daz

[finga]

Either get the hull re-rated or ask the insurance company.
Don't just rip the 25hp sticker off as the serial number tells you (or more importantly the police and insurance company) what the horsepower is.
Some 25's can be done up to a 30hp with next to no effort.

[dogsbody]

Off topic a bit ( sorry Mini )

if your plate says max hp is 250, and the max weight on the plate say 270kg............


now if i was to put a 250hp and it weighed in say at 300kg, what do you do here?


Daz

I'd say your in do do as you are over max weight.


Dave.

[bay_firey]

Too many legal implications if something were to go wrong.

I just wouldn't do it

[TheSaint]

Some 25's can be done up to a 30hp with next to no effort.


That's your best bet mate! Get Tohatsu 25 & at the first service get the restricter plate taken off..

[disorderly]

So is it the extra weight or extra hp that is the determining factor when the manufacturer rates a hull?
We all know that the new breed DFI 2 strokes ie ETEC have a pretty good HP to weight ratio.
And where do ski boats get off?I have seen some thumping big motors hanging off the back of these.
Also those american style bass boats with 200 + Hp on a little 18ft or so hull.

Scott

[freddofrog]

I had similar issue when looking for insurance. Everyone had disclaimers if you go over the recommended power.

I wasn't sure if my motors were over or not so I just went back to the manufacturer and they were fine with it.

Peace of mind really. Imagine falling off and having your boat flying off into some million dollar yacht or worse, an actual person…you'd be in a world of pain.

[builder]

in older boats before july 2006 you only have to worry about insurance
ingrave a 0 on the the plate you are out of warrenty anyway. but if the boat was built after july 2006 its a whole new ball game.. manufactures by law have to place a builders plate on the hull and these days it is not so much the horse power rating but the transom weight that is important, most manufactures have plated less horsepower on there models mainly for the new basic floatation laws that have been put in place ''its all about weight''
the less weight expecially on a tinnie the less foam needed inturn the smaller the bench seats needed and allows more fishing room... for example have a look at a stacer tinnie on how big the back seat is against the front seat.. the reason being
there has to be motor,fuel and battery support wich complies with modern legistation .....

[Dan5]

Hey mini how's it goin?When you say you want more horses to do lower revs just upgrading the same 25 to a 30 won't help you drop any revs in all proberbilaty it is usually more revs from the same engine to give you the extra 5hp.You would be better off and cheaper off looking at your prop selections this also won't interfere with warranty/insurance.But if warranty/insurance is not a worry I'd go a 40hp i had a 385 explorer decked out same as a trophy with a 40hp tohatsu at wot 35.6kts but if you backed it off to 2/3 throttel it still did 25kts easy and become pretty economical.I don't think that 5hp extra would be what your after by the sound of it.Good luck Dan.......

[Nine Lives]

Hi, Ive just had this discussion only afew weeks back,
I went to the manufacturer to ask about rerating my boat for extra 10 horsepower as the 40 & 50 hp merc are the same weight. They told me that the boat could easily handle the extra power but would not rerate as no testing was actully done on this hull for extra hp.

I dont think it realy matters, legaly it probably isnt the rite thing to do but every second small tinnie you see has a much bigger engine than it should. I Agree with Dan a 40hp would be much better.The main thing is that you enjoy the boat.

Or you could get rid of the plate and get some engine stamps and put max hp 40 into the hull, thats all my boat has from new.


cheers Brian.

[bundymal]

hi mini696

mate if going to put a 30hp on wouldn't bother about the cv as only 2 cylinders .go the 30hp 3 cylinder alot more power


cheers
mal

[CreelReaper]

Hey guys,
For what its worth.....everything said above is cool however what you will find is that each boat manufacture has completed testing on specific layouts and motor sizes. What you will find however is that it is the damage and or loss of hull life due to extra 'work' on all the boat's components (transem, stringers welded joints etc)
The extra power would and does cause the boats material to flex more which over time (and sometimes not very long) causes a lot higher stresses. Believe me when I say that increasing a components stresses by even only a small percent can cause substantial damage and even half the expected lifespan. Everyone I have known over 20 or so years on the water that has upped their rated horsepower have been caught and have had to do some serious repairs. Not so bad with tinnies as they can be welded. Fibreglass however is a different matter.
If I was you I would seriously consider strengthening the transom, adding extra supports and crossing my fingers.
I know it is not in the same area but aircraft have very stringent controls in inspection of every component due to extreme stresses at very regular intervals. The stresses in planes are exactly the same as in boats just much higher.
I hope this helps.......

Shane

[mini696]

Thanks for all the answers guys.

[snasman]

What have u got on it currently,most marine motors ie 9.9 and 15,25-30,40-50are the same bore and stroke,and weigh the same this is because they are the same motor but the larger of the two ie the 50 have got larger carbs and better breathing exhausts,so u may be able just to bolt on a larger carby,cheers snas

[bushbeachboy]

G'day Mini,
For starters, don't do anything as silly as trying to mount a 40hp on a 385 Explorer. (I'm assuming that's what your boat is from a previous post). The weight of the motor is far too much for the hull. Quintrex advertise the 385 Explorer hull as being 101kg. If you have added casting decks etc your weight might be similar to the 395 Explorer Trophy which is advertised at 204kg. The maximum hp Quintrex allow for that boat is 30. Most 40hp motors are 90+kg, and will make the boat dangerously unbalanced.

If you decide to go to a 30hp, you take on all of the risk personally if something goes wrong. It may be unlikely, but accidents do happen. Someone advised getting a 30 and changing the stickers on the cowl, or alternatively re-stamping your boat yourself. This is really poor advice. How long do you think it will take for police investigating an accident to find out the truth? If someone has been seriously injured or died as a result of the accident, you will be looking at the possibility of going to jail. Other people who have helped you do the mods might also have some liability.

Is it worth it?

If your boat is performing poorly in its current configuration, try changing something. What about the prop? If you have significantly increased the hull weight but not changed the prop, you might find the motor struggling to cope. A change to a smaller pitch prop might make things a bit better.

Alternatively, can you lose some of the weight? How many people do you take fishing with you? Can you take less stuff on a trip? How many fuel tanks are you carrying?

Something else - when you come to sell the boat, how many people would be interested in buying an overpowered boat?

A question I ask myself all the time is: "Am I being too fussy?" There doesn't appear to be any perfect boat. Would you be better off either keeping the boat and putting up with it or selling it and buying something a bit different?

Lots of things to consider mate.

Cheers

Craig

[mini696]

I have managed to get my local dealer to do a great deal on the 25 Yamaha, this way its the same weight, same power, and I don't have to do anything dodgy to have it put on.

The boat is a 3.9 Stacer but has been gutted, a full floor fitted, plus center consol. Power isn't a problem at all, planes quickly, and top speed is 20knts plus. Cruises very comfortably a couple below that.

I can play with props if I begin to have problems with any characteristics after I purchase the new motor.

[Tailortaker]

my plate says 20hp but I have a 25hp on it, it handles it fine.