Removing Propellers with Explosives

It is done all the time around here on trawlers and larger headboats. Great way to find out if the shaft keyways are cracked
Be sure to warn everyone on the dock or they're liable to jump out of their skins! Also if you have a dip net, get ready to catch the fish jumping out of the water!

I've heard of it for much larger vessels. But never for something that size.

Is this some kind of a last resort?

Ditto. Hope they tried a prop-puller or a hammer 1st. Also hope you have a steel hull.

Hi,

I guess you will soon know, post back and let us know how it went will ya?

down here a short haul is just $5 a ft (a year ago, for a 70 footer) so it's not worth using a diver to swap props... if your props are too damaged to get the boat to a yard i guess it's worth a try but i'd make sure the diver is insured in case something goes wrong and your own insurer backs out.

It's no big deal. Loosen the nut, wrap a couple of turns of primacord held to the forward face of the hub (not the shaft) with modeling clay (plasticine to our Euro cousins) with a cap touched off from on deck and the prop is loose ... usually.

There is no big bang or column of water, no theatrics, no dead fish usually and it is normally anticlimactic. We did it all the time on submarines because we routinely dinged the props for various reasons and all you heard from just a couple of feet above the prop was a snapping noise. The work is done by a rapid shock, not a large displacement of water like you see from a torpedo warhead or other slower burning explosive.

What are your thought about a fiberglass hull?

"What are your thought about a fiberglass hull?"

I wouldn't worry about it at all. The overpressure is so small it is very unlikely to cause any damage. The amount of explosive in a few inches or a foot of detonating cord is very small. It works because it burns so quickly and creates a shock wave that is very sharp but of low duration, a property called brisance, which is just the opposite of what you would want to blow the bottom out of the boat from a charge in the water.

Get someone that has an underwater video camers to record the removal. Obviously, he would not want to be down there with it, but could it be tethered in place? It would be a decent educational and possibly sales tool.

Plus...I wanna see it...

If the prop has pulling holes what's wrong with using a PropSmith?

Check post 4. I'd assume it'd be tried first.

Me too...........

Inquiring minds want to know

Bump...

How'd it work out,Zeke?



I don't assume as you've done, and don't believe everyone knows what a propsmith is- thus the post.

Hi,

Thanks for posting back with your experiences.

It is good to read the outcome of someone's idea/troubles rather than a lot of suggestions and ideas and then the thread goes dead.

It helps to build the knowledge base here at YF and can often be of use to others who know how to use the search function.

+1 to all of the above.

Glad it worked out.
Given:

I think I'd be keeping an eye on stuffing boxes and shaft seals for a while.