Recognize these roof vents?

[FW Kerste]

Hi, my relatively old boat (from '85 or so) has a few leaking roof vents. I am a novice to this and have looked up how to replace a mushroom roof vent but my vents don't seem to have screws. Instead the vents seem to be connected via three steel bits/pins. Does anyone recognize these vents? I would like to know what type of vents these are before I start peeling off the silicon to find out as rain's forecasted. Thanks, FW 

[Tony Brooks]

I suspect they will have been locally fabricated by the builder and probably welded in. Just like the one I had on the Ellis boiler flue. I suspect the boat is at least 30 years old so once the sealer is off you may find rust holes.

[Ian F B]

Picture 3 seems to show a screw head partially concealed by sealant.

It may be worth having a poke about with a pointy tool to investigate ,if it is sealant you may be able to unscrew and investigate further by removing the sealant and getting to the root of the problem.?

[Tonka]

Is that a Mike Heywood built boat. I am sure our 50ft called Tilley had similar vents.

[FW Kerste]

Thanks Tony and Ian. I will have a poke and update you after! Tonka, the boat is made by R&D Fabrications, perhaps they worked with Mike Heywood...

[FW Kerste]

So yes, they were welded on and there was quite a bit of rust underneath. Have taken one apart though and will be treating the rust and replacing it with a mushroom vent. 

 

Thanks all for the help.