inboard info

[spartanpele]

I know I might get ribbed for this thread, but I'll post it anyway.<br /><br />I've always understood two stroke outboard engines, and even the newer four strokes since they remind me of car engines. My brothers, my father, my relatives all have had outboards on their boats. I have an old two stroke on my boat right now.<br /><br />Ok, so here are my questions... and forgive my ignorance. <br /><br />Q: Whats the main difference between an inboard and an outboard other then the obvious fact that the inboards engine in located inside the boat?<br /><br />Q: Is there a difference between an inboard and a stern drive?<br /><br />Q: Are the lower units of the inboards the same as lower units of outboards? (maintenance, etc.)<br /><br />Q: What are the outdrives I hear people talking about?<br /><br />Q: What about tilt and trim with inboards?<br /><br />Q: What advantages are there to having an inboard vs having an outboard?<br /><br />I'm sorry for the long list of questions, but as a life long outboard person, I thought it would be nice to understand how the other half lives..LOL!

 

[Scaaty]

Re: inboard info

You will have to post one question at a time, under the right heading....but best to read through the post, which have already answered all you ask. Your questions require a LIFETIME of learning, so a simple post would cover nothing.

 

[rbezdon]

Re: inboard info

I'll try to answer some of your questions.<br /><br />There are 3 basic types of propeller propulsion configurations (putting aside others such a jet drive) outboard where engine and drive are external to the boat over the transom, I/O (Inboard engine with and our drive also known as a stern drive because is comes out of the stern of the boat) and a true inboard where the drive is usually a straight propshaft under the boat from the engine. In both, the I/O and inboard configurations, the engine is inside of the boat obviously. I think this answers the first question. Your second question should be somewhat answered as an I/O configuration has an inboard engine with and outboard drive (keep in mind that the true definition of outboard just means outside of the boat). The stern drive is just the name of the section of an I/O sytems which is outside of the boat. The lower units of the I/O or stern drives are similar to the lower units of the outboards. Inboards do not have lower units, usually just a propshaft sticking down through the bottom of the boat. I think the above discussion clears up what outdrives or stern drives are (they are two manes for the same part of the I/O system). Tilt and trin on an I/o works very much the same as for an out board. For an inboard it is a bit different and I believe trim tabs are more commen for this application (no need for tilt). There gives and takes for each are numerous. I know one is that an inboard engine usually gives a quieter cruising sound level. It also uses a 4 stroke engine (although now there are also many 4 stroke outboards). Inboards are typically used in larger boats and heavier for the same power. (two stroke engines are more efficient HP vs, size). I hope this helps!!

 

[spartanpele]

Re: inboard info

Robby, it doesn't take a lifetime to answer a few simple questions. For those of us who are mechancially inclined, a few simple answers would have been sufficient. It would have been better for you to simply say nothing then post your rude response.<br /><br />Vatter, thanks for the well spirited response. I appreciate the straight forward answers. You answered most of my questions. I can get more in depth answers by looking through a repair manual or by chatting with the I/O owners at the dock.<br /><br />I guess I'll go back to the outboard side...<br /><br />Thanks!

 

[imported_scott_m]

Re: inboard info

Actually, inboards have no tilt or trim - it is a fixed propshaft supported by a strut and bearing. Some boats are equipped with tabs to modify running angle. Good thing about I/O or outboard is the ability to get in much shallower water - I can't move my running gear. Also, there are two varieties of inboard - straight drive and V-Drives...in straight drive the motor is installed with the front of the motor facing the bow, then a transmission off the back of the motor, then the coupler, then the shaft passes thru the hull. In a V-Drive config, the front of the motor faces the stern of the boat (most common in 'express' type boat configurations), then the transmission, then the V-drive which turns the direction of the propshaft 90 degrees, then coupler and shaft. Some will say that the inboard is a heck of a lot more fuel efficient than the I/O because you have less running gear in the water (drag), but generally the I/O will be much more manuverable at planning speeds. The inboard (especially in twin configuration) will handle MUCH better around the dock. A single inboard can be a real bear (trawler style hull)...in this case, I'd rather have a single I/O or outboard.<br /><br />Hope this helps...inboards are great.

 

[pete44]

Re: inboard info

I have an 87 Searay I/O Bowrider..Things I have heard is outboard is louder..blocks your rear view(especially if skiing)otherwise..Outboards in a runabout config gives you more room in the rear (no engine cowl gives you a nice bench/storage area) and you can tilt outboard totally out of water) to where my I/O the prop just comes below the waterline...My boat has a 12" draft with drive up..which isnt bad for a 1880 lb 17 footer..My main reason for the inboard they just look nicer/sleeker than an outboard..good for a runabout anyway....hope this helps..pete44