Living in 150 plus inches of rainfall each year requires some serious waterproofing. I have found a product called 'Dry Camp' heavy duty level, is working well for my fly bridge chair covers. I use on my 'carhart' coveralls, golf jacket, cotton coveralls. Yes, after washing the clothes require a new spray. I believe the product manufacture is Coleman, away from home at the moment so I can't look at the can.
Would post a photo of our boat, but just not technically up to speed. Still have a cell phone with a rotary dial!
27' Marben trawler