Bio-fouling problem

No idea about your home waters but here in south Florida most boats get cleaned by a diver once a month, they check and replace zincs too, for $2 a foot (plus since costs obv)

We usually get two years out of bottom paint between bail outs

Our insurance company has been requiring out of water surveys and messing up our hauling schedules.
We have gone 3 years (twice now) between hauls and contribute this fantastic performance to our diver who dusts off the bottom every month. I think we could easily go 4 years if the insurance company leaves us alone.
Once silt and slime covers the paint, the best poison can not stop what adheres to the bottom. Once that barnacle forms a shell, the paint is has lost any gains.
Paint will not stick to running gear for long. Our diver does some cleaning here. Zincs about twice a year.

With horror in our eyes, We have witnessed results from other diver service. You must find a good diver and stay with him.

Stay around the marinas and watch every haul out. Find out who has been diving the ship. Evidence will come quickly on your decision who to use.

Divers here are monthly. Usually $2.50-3 per foot per month, plus zinc prices as needed. A diver is about 1/4 the price of haulout and pressure wash. 7 out of 10 divers SUCK, so find a good one. I ran one to the yard for an owner, who had a monthly diver and the 2' below the waterline were perfectly clean and below that 2 YEARS of growth. I usually do bottoms every 18 months (hauled/painted) with ablative paint. If the boat has hard paint, some of them do go as long as 3 years, but not ablative.

I'm going out on a limb and say if you are a master mariner as your profile states those seem like odd questions.

Odd in that I have a hard time believing you would not know the answers, and if not, you could find out simply by talking to the guy in the rig on either side of you.

down here in Trinidad the sea temps are quite high and we require a diver to wipe of the slime every two weeks. I would normally use a hard paint on my 38 ft sportfisherman and have had the paint last me 3 years between haul outs. The paint seems to wear away the most around the waterline above the chine where the sunlight increases the growth rate, hence requiring the diver to clean that area more often.

yea I normally add an extra 2-3 coats to the area above the chine, looks like I will have to add more next time.

hahaha good one, nah its normal 3m scrubbing pad. like I said, cant really complain about my bottom paint lasting 3 years in the tropics

Hard paint lasts much longer than ablative and is more effective, but also the paint you're getting in Trinidad has better ingredients that are outlawed in the U.S.. What brand of paint are you using? Interlux ultra?

The paint that I had on for the last 3 years was a Carboline hard paint sold by the local distributors here in Trinidad, not 100 % sure what exact product
series. Unfortunately they stopped importing the hard paint in blue, and I did not want to go with black paint. So I have since reapplied a different brand of blue paint, and I will have to see how it holds up.

I have attached a picture showing the condition of the paint after 3 years.

I have noticed boats tied close to the docks fuel pumps loose the top inch or two quickly. Just a few drops out the vents while fueling leaves a wide solvent cloud on the water. Gentle rocking of the boat and lil ripple on the water helps insure the top couple of inches of bottom paint get softened. Then ad UV, and more slime.