Propeller Spare Parts Update

Whole nut, half nut, shaft key and cotter pin. But are they enough?

Having spare parts easily available is a smart thing to do for many below deck systems aboard your boat. In our classes we always advise boaters to carry extra propeller shaft nuts, cotter pins and shaft keys. We’ve even created a Spare Parts List PDF for new boat owners to consider. But here is an update: There is more to add to your spare parts list if you have an outboard motor including your dinghy… a thrust washer! So let’s dig into the why of it.

Propeller Spare Parts Are Important

If a diver is working on your boat’s propeller and drops something into the mud, that could be a problem. Remember magnets do not attract bronze or stainless steel. So having a spare shaft nut, cotter pin or shaft key can be a great help. Some boaters even carry spare props but that is a heavy, expensive and difficult item to stow aboard many boats. The larger size propeller may be easier to find if dropped in the mud than a smaller accessory part. BUT the diver should have a rope attached to the propeller just in case.

Why You May Need More

Today I heard a new story. A friend was cruising the Florida Keys in their 28 foot Grady White and lost a propeller off the outboard. The propeller just decided to take off and leave the outboard motor. The owner reports that they DID NOT hit anything. The propeller was there and then it wasn’t. Yup, cruising along in the middle of a fairly deep channel and Whoosh! it just wasn’t there anymore.

At first, they thought they were prepared by having a spare prop, nut and cotter pin. What they did NOT have was a replacement thrust washer! They thought that if they banged the prop then they would just change it. Frankly, they did not know a thrust washer even existed. Thrust washers are flat washers that are located between a rotating surface (Propeller) and a stationary component (The outdrive).

Now that they diagnosed the need for a thrust washer they thought the problem was solved. Alas, none were to be found in Islamorada Florida Keys. So they had to overnight freight it in and to put the spare aluminum propeller back on. Meanwhile, a new stainless steel prop has also been ordered and is on the way.

Now they have nuts, cotter pins and spare thrust washers for their outboard motors ready for any future adventures.

Ask Captain Chris

We are delighted when you share your experiences so other may learn. Join us at a future seminar – Cruising 101 or Introduction to Boat Systems and learn what to know before you go. Ask Captain Chris. 772-205-1859