Defender and West Marine (recently filed for bankruptcy) were taken over by private equity and I think you see the resultsf. I am not sure if this was the whole cause of their downfall. Certainly there were problems in the retail Marine industry before either was taken over, but I have little respect for how the private equity vultures work and the kind of "expertise' they bring into businesses they take over (Vet clinics, dental offices have been primary targets). Now you are seeing Safe Harbors taking over marinas and wringing the last dollars they can out of them as they follow the West Marine corporate model of bigger is better and offering small business folks retirement deals they cannot refuse. Seems like the modern business model is just about quarterly profit and customers, employees, and long term investors be damned.
As a pro, I still love my West Marine (Port Supply) in the Annapolis area--it is well-stocked, prices are decent enough, and all of the supplies are OEM or equivalent quality. It is great for wire and connectors, switches/breakers/fuses, hoses, pumps, filters, oils, impellers, batteries and chargers, etc. Most specialized or big-ticket items I simply order from Amazon or an online marine chandlery/wholesaler.
I talked to the manager at my West Marine location recently and he said the company is not going under--only that they are restructuring, dumping locations that are not profitable: i.e. getting out of some bad site leases. It really sounds like the business got too bloated over the 2000s and they are trimming the fat so it survives; they have also really improved their website and web-ordering process in the last few years as well. I am rooting for them (and the other marine chandleries like Faucet, Defender, etc.). I have always found the staff to be decent enough, and at least willing to try to help as well.