Difference between revisions of "Blisters on a Rudder"

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This is not obvious in the pictures.
 
This is not obvious in the pictures.
 
After opening up some of the blisters they all were wet inside.
 
After opening up some of the blisters they all were wet inside.
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 +
 +
==Drying Out==
  
 
[[File:Drying_out.jpg |400px|]]
 
[[File:Drying_out.jpg |400px|]]
 +
  
 
The hole along the bottom of the rudder was opened up and the rudder set up in a shed to allow it to dry.Water continued to drip out through November, December and January but at the beginning of February it was dry enough to pass over to the local fibre glass shop with instructions to repair the bottom and seal the holes up.
 
The hole along the bottom of the rudder was opened up and the rudder set up in a shed to allow it to dry.Water continued to drip out through November, December and January but at the beginning of February it was dry enough to pass over to the local fibre glass shop with instructions to repair the bottom and seal the holes up.
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It was decided that the whole of the rudder needed to be peeled.
 
It was decided that the whole of the rudder needed to be peeled.
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==Inside the Rudder==
  
 
[[File:Test_core.jpg|500px|]]   
 
[[File:Test_core.jpg|500px|]]   
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There was concern that the steel work inside might have been compromised by the water. So a test core was drilled and a hole routed out near the shaft to expose the steel underneath.
 
There was concern that the steel work inside might have been compromised by the water. So a test core was drilled and a hole routed out near the shaft to expose the steel underneath.
  
The rudder was found to be cored with a black aireated resin which had not absorbed water. The water inside the rudder was between the core and the inside of the gel coat resulting in the large area blisters observed.
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The rudder was found to be cored with a grey aireated resin which although crumbly had not absorbed water. The water inside the rudder was between the core and the inside of the gel coat resulting in the large area blisters observed.
  
 
[[File:Close_up_of_inside.jpg |400px|]]
 
[[File:Close_up_of_inside.jpg |400px|]]

Revision as of 17:21, 12 March 2019

The Story

I had been aware of blisters in the rudder for some time but chose to ignore them until I damaged the leading edge of the rudder on a sand bank in the middle of the Thames Estuary (Middle Sand). At the same time I was aware of a leak around the rudder tube that required the rudder to be dropped for investigations.

The rudder.jpg

After lift out a hole was dug and the rudder dropped.

Rudder removed.jpg


Leading edge.jpg Top of rudder.jpg

The rudder was damaged at leading edge corner and water was dripping out.

With the rudder upside down water also came out from around the top edge.

Poppedblisters.jpg

Since repairs were obviously going to be required to the bottom of the rudder I decided to investigate the some blisters.

The blisters were not what I expected as osmotic blisters seeming to be more like the intact gel coat being forced away from the core over an area of about 12 to 1.5" diameter.

This is not obvious in the pictures. After opening up some of the blisters they all were wet inside.


Drying Out

Drying out.jpg


The hole along the bottom of the rudder was opened up and the rudder set up in a shed to allow it to dry.Water continued to drip out through November, December and January but at the beginning of February it was dry enough to pass over to the local fibre glass shop with instructions to repair the bottom and seal the holes up.


The bottom was repaired but when the holes were investigated inside it was found the gel coat was damaged. There were holes possibly as a result of previous attempts to repair osmotic blisters. The holes had been filled but had not been reinforced with glass and the filler was actually soft.

Peeled.jpg

It was decided that the whole of the rudder needed to be peeled.

Inside the Rudder

Test core.jpg


Inside the rudder 1.jpg

There was concern that the steel work inside might have been compromised by the water. So a test core was drilled and a hole routed out near the shaft to expose the steel underneath.

The rudder was found to be cored with a grey aireated resin which although crumbly had not absorbed water. The water inside the rudder was between the core and the inside of the gel coat resulting in the large area blisters observed.

Close up of inside.jpg


Test hole refilled.jpg