Pianotech

I purchased an excellent dehumidifier that has a pump to expel water down a drain in the event the tank fills up. it can be controlled from a phone app etc I will get back to you on the exact model it was made by LG I had to track down a place that had it in stock since it was sold out in a number of places. It is probably better to use it away from the piano not under it and put a beefed up partial dampp-chaser with humidistat and a dehumidifier under the keybed centered under the keys . Adding an undercover will help create a micro environment . In the event of a power failure I believe it can restart itself .

Some of the raised beach homes here can have no finished garages or storage .They have open louvers all around each side and back with regular garage doors. Some customers I have will enclose their vehicles in portable garages with zippered flaps to reduce exposure to corrosive air 

I have a dehumidifier in my basement that drains directly into a floor drain. Is that a possibility along with being plugged into a pianolifesaver humidistat?

As Wim mentioned salt air is highly corrosive Cars that are parked in driveways or under raised beach houses are rusted out quickly underneath and metal light fixtures rust and get pitted. The salt air destroys the fins and metal on airconditioners no matter the brand. I had 2 customers with very expensive beach homes and Yamaha Grand Pianos. One had a woolen string cover and Dampp Chaser System and kept the humidity and temps in the safety zone. The did not leave windows and doors open and the piano was fine. Second person did not have a string cover or Dampp Chaser and liked the sound and smell of the ocean The strings were full of rust and the action barely played . Perhaps building something like a stage garage or even using a custom made shed may slow down the distructive combo of heat humidity and dew point moisture plus salty air . It sounds like the setup is like a carport. I have seen several pianos parked that way. None have fared well. Maybe an enclosure with screens and plexiglass panels plus a dehumidifer and woolen string cover will help 

A dealer I worked with bought a near-new Bosendorfer 7' that had been near the beach here in Southern California. The strings were hopelessly rusted and even the paint on the plate was corroded.  After refinishing it was a fun restringing and the end result was passable (it would have been better if I had restrung more in my long career).

It gave me more respect for the corrosive effect of salt air.

I once restrung a Steinway M and after it was delivered the strings only lasted 2 years before they were badly rusted.  This piano was miles inland, but along the Wilshire corridor where nightly ocean breezes pushed salt air in though a window near the piano.  I only cleaned the strings and it lasted many years, but the rate of rusting was frightening to a young technician who wondered what I had done wrong.

I have a small GE dehumidifier in my basement that runs 24/7. It is short enough to fit under a grand and has a hose attachment. They may even make a smaller one. However, expect to replace it about every 2-3 years as the stuff they make today is not as robust as the units we used to have (back in the day) which kept going for decades.  

Peter Grey Piano Doctor 

I've heard of VCI emitters preventing corrosion of metal. Anyone have experience with these products? Amazon.com: Bullfrog 13219 Bull Frog 91321 Rust Blocker Emitter Shield : Automotive

I just found out that the VCI emitters work best in a sealed environment. Also the molecular protective coating they provide on metal surfaces only lasts a few weeks. That said, if I had a beloved piano in a coastal environment, using them would be a reasonable habit to adopt: once a month, install an emitter and pallet-wrap the piano for three days. I've seen coastal pianos develop rust so fast, it's unbelievable.

Interestingly, here in the Puget Sound area, there's plenty of salt water, yet almost no rusting. Being an inland sea, we don't get the constant ocean wind. It's not uncommon to find 100-year-old pianos with very little rust or corrosion.

Would anyone be interested in trying an experment?

I was talking to Evan Silo from McLube and they make a music string sealer that some guitar manufacturers used to prevent the hand oils from attacking the strings.

He thought it would work well on piano strings to prevent the salt from attacking.

He offered to send a sample but I live in the desert and just asked him about it while I had him on the phone because of this thread.

If anyone is interested in testing it on piano strings exposed to the ocean I can send you his contact info.