Case study: Marine growth (algae) and its effects on Hull cleaning (winter)

Abstract: This study was conducted by Scuba Duba Corp. at Shoreline Marina, Long Beach, CA in the months of February and March, 2011.
The purpose of this study is to show how marine fouling progressively increases its algae density, especially in those areas/boat parts not protected by anti-fouling paint, throughout a month period in the cold season/winter.

Why are we doing this?
As hull cleaners we are not surprised by the growth density accumulated in a short period of time. Even in winter time, hull cleaners face this reality daily.

We understand that the customer's perspective might differ and we hope this simple study helps boat owners visualize this reality.

“A well executed bottom cleaning strengthened by a solid quality control program will contribute to a cleaner bottom for a longer period of time, considering the marine growth levels in Southern California”

We focused the test on three different surfaces: 
1-Boat hull painted with anti- fouling paint.
2-Boat hull with a very poor bottom paint condition / bare gel coat.
3-Metal parts (not bottom painted): Out-drives and trim-tabs.

1-Boat hull painted with anti-fouling paint:

On this set of pictures we targeted the waterline, at the stern including the exhaust. The hull on this boat was recently painted (four months) and both paint coverage and anti-fouling quality are in excellent condition. We can clearly see the growth progress throughout the weeks, even with new anti-fouling protection and the slower growth time of the year (winter).

2-Boat hull with a very poor bottom paint condition / bare gel coat:

On this set of pictures the target was also the waterline at the bow of the boat.

The hull on this boat hasn’t been painted in ten years. Both paint coverage and anti-fouling quality are nonexistent.

Unfortunately the water visibility in pictures (after 3 and 4 weeks) was not as expected, and the growth level is not very clear in the pictures.

Three weeks after the cleaning, the top part of the waterline is covered with 2-3” of algae, increasing to 4-5” long in just a week (week 4).

3-Metal parts (not bottom painted): Out-drives and trim-tabs:

On these sets of pictures we targeted unpainted metal parts such as: Out-drive / trim-tab.

Surprisingly, almost no growth activity is reflected in the first week after the cleaning, but a progressive voracious growth increases in weeks 2, 3 and 4.

          Out-drive

 

          Trim-tab

Conclusion: In the marinas of Southern California, marine fouling levels are high through out the year with a pronounced increase in the warm season (spring-summer). A well maintained boat hull requires bottom paint, scheduled every 2-3 years and a monthly hull cleaning for boats with good bottom paint condition (biweekly for unpainted or poorly painted hulls). These measures are fundamental for a healthy boat hull and its metal parts and for the best fuel economy.

Hernando Esparza