Mariner 3.3hp 2 stroke shear pin question

[MINESAPINT2]

I have been having problems getting the prop off so eventually decided to apply a bit of winch pressure. When it popped off the problem became clear. The drive/shear pin is 4mm solid stainless which at some point in the engines 20 plus years existence has become bent at one end to nearly 90 degrees. When I pulled the prop off the bent pin caused a bit of damage to the centre of the prop (tore some of the plastic) so it is not possible to fit a new drive/shear pin in the intended manner. I decided to drill straight through the prop with a 4mm bit in exactly the same location as the the original pin. I would judge the operation a success and just need a longer pin to pass through the prop.

This got me thinking about the material the original pin was made of and how a plastic prop is expected to shear a 4mm solid stainless pin, or perhaps it is not intended to shear??? just to apply the drive???

A simple solution for me at the moment would be to put a 4mm stainless split pin right through the prop and shaft.

Engine used on my tender.

Advice appreciated

Thanks

Mike

 

[dansaskip]

Shear pins are well - designed to sheer - using stainless for a pin is just wrong. They should be of a bronze type material

 

[lustyd]

And yet Pacer seem to supply them that way Mariner 2.5 3.3 3.5HP 2 & 4 Stroke Shear Pin Packs – Pacermarine

 

[andsarkit]

The plastic prop has a brass/bronze shear pin and the stainless pin is used with a metal prop.
I got a length of brass rod from B&Q for about £5 which made a lifetime's supply of shear pins. Needless to say I have not needed one since the original one sheared when I hit an underwater obstruction .