boat overloading damage engine?

[areeeeeph]

many people says boat overloading damage the engine.
is that true? if it is true, how it damages tge engine?

[boscoe99]

I am one of many that say that an over loaded boat can damage an engine. Or put another way, if the motor does not have a propeller installed that allows the motor to turn XYZ RPM at WOT, whatever the weight of the boat may be, the motor can be damaged.

And the damage can be terrible. Broken pistons, rods out of the sides of the block etc.

For any piston engine there needs to be a certain relationship between the intake manifold pressure (think throttle position) and the engine RPM. If the throttle is wide open there will be maximum intake manifold pressure and maximum combustion chamber pressures when the spark plug does its magic. If the engine RPM is too low, then an event referred to as detonation can occur. Think of it as a violent explosion as compared to a steady burning of the air/fuel mix. An explosion that can tear the motor apart.

How to avoid this? Simply do a WOT RPM check. With the boat loaded as it will be used make sure that the motor will run at or near its red line RPM. A boat lightly loaded my need a 19" pitch propeller. Take the same boat and load it up and the propeller may need to be a 15" pitch. Or lower. Depends upon the load in the boat.

[areeeeeph]

how much weight can 25hp outboard handle?

[99yam40]

how much weight it can push depends on the hull and the prop

smaller the motor and larger the load will require a smaller pitch prop to turn the proper RPM and push the load at a slower speed

[DennisG01]

how much weight can 25hp outboard handle?

The two answers above give you the info you need to figure it out (anything I add would just be restating what has already been said). One is short and sweet, the other more technical. Get off the computer and go out there and figure it out! Unless of course, going out and playing around on your boat is a bad thing...

[boscoe99]

how much weight can 25hp outboard handle?

Many thousands of pounds I would speculate. I have seen a T25 installed on a 28 foot boat for use as a kicker. The boat must weigh upwards of 10,000 pounds I would guess.

All that is needed is to find the appropriate propeller for the boat (weight) in question.

[Jason2tpa]

how much weight can 25hp outboard handle?

What's the nature of your question? Because your question is so nonspecific, I believe you're getting answers here that may not even apply to what you're trying to determine.

As boscoe mentioned below, a 25hp can push a ton a weight, literally and metaphorically. So why are you asking how much weight can be handled?

Answer that and I believe you'll receive the information you're looking for.

[rodbolt17]

delivered a Carolina skiff 24 some years back.
it left with an F150 and a center console and a cooler seat,
it came back with holes in two pistons and seating for 12.
to much prop for 12+ persons.

[boscoe99]

delivered a Carolina skiff 24 some years back.
it left with an F150 and a center console and a cooler seat,
it came back with holes in two pistons and seating for 12.
to much prop for 12+ persons.

Let me guess. Pistons two and three. Did the boat also have a white transluscent gasoline tank on deck exposed to the sunlight?

[99yam40]

Let me guess. Pistons two and three. Did the boat also have a white transluscent gasoline tank on deck exposed to the sunlight?

was it yours?
or one you saw down south?

[boscoe99]

was it yours?
or one you saw down south?

Nope, not mine. Not one I saw down south. One of many I saw here in the good ole US of A.

Carolina Skiffs used to be notorious for using white gasoline tanks out on the deck. Or under a non-enclosed center console. The gasoline could get seriously degraded due to sunlight acting upon it.

Now the F150 does not have a knock sensor. It has a relatively high compression ratio. Just like the number two cylinder on a big block HPDI is usually the first to go, numbers two and three on an F150 are prone to failing before the other pistons.

Take an F150 that is over propped (or boat over loaded) and run it on a bit of degraded gasoline and bad juju is bound to happen. Then blame it on the Yamaha motor since that is the part that is now smoking.

[99yam40]

anyone ever figure out why #2 and/or 3 are the 1st to go on these motors??

[areeeeeph]

i am using 25hp mercury in 19ft dinghy. normally i load 10 people while travelling..is it too heavy for the engine?
my dad always say its too heavy for engine and could damage it

[TownsendsFJR1300]

i am using 25hp mercury in 19ft dinghy. normally i load 10 people while travelling..is it too heavy for the engine?
my dad always say its too heavy for engine and could damage it

As posted above, simply re-prop so your engine CAN REACH the RECOMMENDED max RPM range WITH your load.. If it isn't already

Then your good to go (pun intended)



.

[cleddau1]

Is it not the resistance of the boat through the water that is relevant rather than the weight? Resistance through the water is a function of hull length and configuration, wetted area, sea state, windage of superstructure, and any headwind. Only the wetted area will increase with load.