Driving a 4.3 Mercruiser

[dtrman1318]

I am going to buy a new boat with an I/O engine on it and this being my first I/O boat I am not sure about how to drive it. I have always used Outboard engines and I was wondering if there was any difference in operating an I/O engine. Your help and tips would be much appreciated. Thanks

 

[HT32BSX115]

Re: Driving a 4.3 Mercruiser

Howdy,


If this is a new boat, be sure to carefully read your owners manual.

There's a lot of fairly good info in there on what you need to do to operate your new engine.

It's not really much different from an outboard when operating it.....(same steering wheel and single handle throttle/shift control)



Just be aware that you cannot see the drive and placing it in gear can give you quite a surprise if you don't know which way the drive is pointing and you "pour the coal" to it!! (it's easy when you can see the outboard)

Probably the most important difference is a safety item...... Your engine is completely enclosed.... There is an exhaust blower in the engine compartment that MUST BE OPERATED prior to starting the engine to evacuate any fuel vapor that might be in there. Failure to do this prior to EVERY START could cause an explosion and fire!

Also, if you have a swim step on the back of your boat, make sure everyone in the boat knows that they may not sit or ride on it if the engine is running.... Many people have drowned from carbon monoxide poisoning.....

And then of course, there's that propeller!!


Your owners manual will tell you all about it!


Cheers, and


Good luck with the new boat!


Rick

 

[achris]

Re: Driving a 4.3 Mercruiser

.... Many people have drowned from carbon monoxide poisoning.....

????????

Would you like to rephrase that?

 

[Fordiesel69]

Re: Driving a 4.3 Mercruiser

Also to add to what others mentioned, with an outboard, you can pretty much tilt the engine up as much as you want while running in case you are too shallow. With an I/O, there is a limit at which the u-joints can withstand. If you tilt too far, you can tear up the coupler, yoke, and u-joints in a matter of a very short time.

However, there is usually a "Tilt" switch, and a "Trim" switch. If you use the trim switch exclusivly out on water, you can safely operate it anywhere in that range. Tilt is used to get it in + out of the water.

Also you need to make a little note to put the drive down when you start it for ANY reason, even if you have the shift lever in neutral, it is common to forget in a hurry.

 

[Philster]

Re: Driving a 4.3 Mercruiser

Many outboards can't be trimmed up/down. On a sterndrive, you need to raise the drive to build speed. Failure to do so will keep the bow buried, and your engine will probably max out around 75% of it's total RPM range (or even less than that).

First, with the bow buried and the hull mostly wet and in the water, you are not positioned to handle certain waves/seas/wakes. That is dangerous. You could stuff the nose into a wave or create a terrible ride and not be able to raise the bow as needed.

Second, if you have a 5000 RPM redline, and you have the motor trimmed all the way down, and you are trying to build speed, the engine hits a wall at around 3,800-4,000 RPMs, and at that point you are lugging the engine, which puts a tremendous amount of strain in the internals. You don't have enough hull/bow out of the water, and the engine is fighting this massive resistance. As speed builds, you need to raise the outdrive via the 'trim up' control to a point where the boat builds speed, but not so far that too much of the drive is out of the water, causing you to lose control (porpoising).

It is something that must be learned, and is different with every combination of the boat/hull/drive/passenger/load/weather/seas.