What size anodes?

[the griff]

My falcon spc23 is out of the water for the winter and I have managed to remove what was left of the anodes on the trim tabs this afternoon to replace them. Boat is 23 feet long with a kad 32 and single duoprop outdrive. It's moored in fresh water but I do go out to sea in it during the summer so after lots of reading I have decided to put aluminium anodes on. Will 100mmx 30mm top and bottom of trim tabs be too thick or would 90mmx20mm be better?

 

[Piers]

My falcon spc23 is out of the water for the winter and I have managed to remove what was left of the anodes on the trim tabs this afternoon to replace them. Boat is 23 feet long with a kad 32 and single duoprop outdrive. It's moored in fresh water but I do go out to sea in it during the summer so after lots of reading I have decided to put aluminium anodes on. Will 100mmx 30mm top and bottom of trim tabs be too thick or would 90mmx20mm be better?

As a guide, anodes need to be changed if they are 50% used. I have Play d'eau lifted annually to check the anodes. If any anode has less than 50% left, I increase the size of the replacement. Simples.

 

[oldgit]

A single circular anode on TOP of the trim tab is the usual practice .
Nothing but the bolt head disturbing the water flow underneath tab.
Suspect my trim tabs a much larger than yours and single anode about 100mm x 30mm more than does the job.
Usually 50 % of the anode still there after 12 months.

 

[the griff]

A single circular anode on TOP of the trim tab is the usual practice .
Nothing but the bolt head disturbing the water flow underneath tab.
Suspect my trim tabs a much larger than yours and single anode about 100mm x 30mm more than does the job.
Usually 50 % of the anode still there after 12 months.

Just putting on top would make sense, the ones that were on were fit top and bottom with tabs sandwiched between, I presumed that was standard practice. Maybe a 90x20 on top of each might be the way to go.
What's people's opinions on aluminium for a boat moored in fresh water but goes out to sea?

 

[Piers]

What's people's opinions on aluminium for a boat moored in fresh water but goes out to sea?

A common question that's asked. Answer: fit the anodes applicable to whether you spend more time in salt water or fresh water.

 

[Momac]

What's people's opinions on aluminium for a boat moored in fresh water but goes out to sea?

Aluminium is my choice in the same circumstances.

 

[the griff]

A common question that's asked. Answer: fit the anodes applicable to whether you spend more time in salt water or fresh water.

The reason I had decided on aluminium was they say they are suitable for fresh, brackish and salt water on many sites, has anyone used aluminium that's in the same situation as me, moored in fresh majority of time but do venture out to sea on a weekend.

 

[rlw]

Aluminium is good for your use. Had them on my latest boat and noticed an improvement in protection from previously using zinc on a previous boat but both with 290 DP drives.
For occasional visits to saltwater they are find but I moved to a saltwater marina this year and in my case they would not last the season. Had a hole in a ring anode after 4 months.
On freshwater they would be fine at the end of the season.