How boats do to not let water in by the propeler?

Question

How boats do to not let water in by the propeler?

Answer 1

Where the propeller shaft leaves the boat there is a seal around the shaft to keep the water out. There are many different types and designs of shaft seal but they all do the same thing, they seal around the shaft whilst still allowing it to rotate.

Answer 2

I'm guessing your talking about ib/ob.They have a shaft seal on them to keep the water out.

Answer 3

I would assume you are talking about an inboard.  In an inboard engine the drive shaft goes right through the hull - what keeps water from getting in that hole is the packing, which is basically string with wax all over it - that wraps around that shaft on the inside of the boat.  Inboard boats will almost always drip a little bit from this area, usually something like one drop ever 10 or 15 seconds... once it starts dripping more - it is time to replace the packing

Answer 4

There are seals there, different kinds depending on the boat. They can leak. Animals have been known to chew on some and sink the boats.

Answer 5

Seals and bellows

Answer 6

The link below shows a diagram of how a stuffing box works for an inboard drivetrain (ignore the "asbestos" label - modern packing is some sort of fibrous material that's impregnated with wax, teflon, or some other lubricant). The stuffing box is located inside the hull, behind the transmission. Tightening the gland nut(s) compresses the packing and completes the seal. If it's over-tightened, there's too much friction and the shaft will score/pit. Tighten too little and water intrudes.  Note that many boats have a large, single gland nut that encircles the shaft - the principle is the same: it compresses a few rings of packing to complete the seal.

Proper maintenance of a stuffing box is to keep dripping to a minimum, but not to tighten the gland nut so much that the shaft/box heats when underway - warm is okay, hot is not.

Unless the stuffing box is inaccessible, re-packing it can be done in the water. Believe it or not, not much water comes in when the packing is removed. It's best to have someone who's done it before help you through the first time.

Answer 7

DDREW said the same as all the others.( with explanation)

Its still a seal.