greenhorn bottom job questions

[NorthernMac]

Hey folks,

Just pulled my boat for the first time since the survey 6mo ago (which I wasn’t here for, yeah I know...).

So the plan here is to replace one small through hull for a propane vent

Fix any blisters, surveyor said he saw one, I’m not seeing it?

Re up bottom paint (thinking of using the 66, other thought was the extra as I might end up in more fresh brackish water)

Rudder is getting a keyway installed ($260 and a few days at the machine shop) for a arm for the below deck autopilot I’m installing.


So basically I was going to hit it with a sander with 220, wipe down with alcohol and put on 2 coats with a third at the waterline, 3 gallons I think, roller with a brush after to smooth it,

Using frog tape to mask the waterline

I was also go to re do the stuffing boxes (rudder and prop) with new stuffing, prop was starting to drip a bit more.

And maybe add a new sounder transducer

New zinc on the prop shaft

Any suggestions, or things I should also do or not do??


Thanks,

[Orion Jim]

Originally Posted by NorthernMac

Hey folks,

Just pulled my boat for the first time since the survey 6mo ago (which I wasn’t here for, yeah I know...).

So the plan here is to replace one small through hull for a propane vent

Fix any blisters, surveyor said he saw one, I’m not seeing it?

Re up bottom paint (thinking of using the 66, other thought was the extra as I might end up in more fresh brackish water)

Rudder is getting a keyway installed ($260 and a few days at the machine shop) for a arm for the below deck autopilot I’m installing.


So basically I was going to hit it with a sander with 220, wipe down with alcohol and put on 2 coats with a third at the waterline, 3 gallons I think, roller with a brush after to smooth it,

Using frog tape to mask the waterline

I was also go to re do the stuffing boxes (rudder and prop) with new stuffing, prop was starting to drip a bit more.

And maybe add a new sounder transducer

New zinc on the prop shaft

Any suggestions, or things I should also do or not do??


Thanks,

Just pulled my boat for the first time since the survey 6mo ago (which I wasn’t here for, yeah I know...).

So the plan here is to replace one small through hull for a propane vent

(Don’t quite understand this. A vent for a propane locker should be well above the waterline. Perhaps it was plastic and is cracked?)

Fix any blisters, surveyor said he saw one, I’m not seeing it?

Re up bottom paint (thinking of using the 66, other thought was the extra as I might end up in more fresh brackish water)

(Micron 66 will fail in fresh or brackish water, Extra is ok in fresh)

Rudder is getting a keyway installed ($260 and a few days at the machine shop) for a arm for the below deck autopilot I’m installing.


So basically I was going to hit it with a sander with 220, wipe down with alcohol and put on 2 coats with a third at the waterline, 3 gallons I think, roller with a brush after to smooth it,

(120 grit will get you a smooth finish, 220 grit will get you lots of exercise for the same result. Cheap paint thinner is better than alcohol, but if you have access to a hose you can just wash the bottom with Dawn to remove the dust and hose down well)

Using frog tape to mask the waterline

I was also go to re do the stuffing boxes (rudder and prop) with new stuffing, prop was starting to drip a bit more.

And maybe add a new sounder transducer

(Airmar makes them and all the popular instrument makers just rebrand them. Just look for the best price.)

New zinc on the prop shaft

Any suggestions, or things I should also do or not do??

[boatpoker]

Zinc anodes are only good for salt water.
Magnesium anodes are only good for fresh water.
Aluminum anodes are good for salt, brackish and fresh water.

[chrisr]

you will find antifouling is extremely difficult to sand dry. it clogs the paper almost immediately

as you can't use wet sanding with a machine without electrocuting yourself, most folk settle for the old fashion hand sanding with wet n dry sand paper

a boat your size could be knocked over in a day or 2 - with a couple of mates and a couple of cases of beer.

good luck

cheers,

[NorthernMac]

Originally Posted by Orion Jim

(Don’t quite understand this. A vent for a propane locker should be well above the waterline. Perhaps it was plastic and is cracked?)





(Micron 66 will fail in fresh or brackish water, Extra is ok in fresh)


(120 grit will get you a smooth finish, 220 grit will get you lots of exercise for the same result. Cheap paint thinner is better than alcohol, but if you have access to a hose you can just wash the bottom with Dawn to remove the dust and hose down well)


(Airmar makes them and all the popular instrument makers just rebrand them. Just look for the best price.)

I’m adding a water maker so I’m swapping a old plugged 1” above water line for the vent, and using the side slightly larger one for the AC and water maker I’ll be installing.

I’ll go for the extra, thanks!
Boats mostly in salt, but with my work I travel and it wouldn’t be crazy for me to end up somewhere

So 120 on a rental vac sander, Dawn and hose?
How far do I have to take it down?

[NorthernMac]

Originally Posted by boatpoker

Zinc anodes are only good for salt water.
Magnesium anodes are only good for fresh water.
Aluminum anodes are good for salt, brackish and fresh water.

So any draw backs to aluminum on a SS prop shaft? Any reason everyone doesn’t just default to Al?

[thomm225]

Originally Posted by NorthernMac

I’m adding a water maker so I’m swapping a old plugged 1” above water line for the vent, and using the side slightly larger one for the AC and water maker I’ll be installing.

I’ll go for the extra, thanks!
Boats mostly in salt, but with my work I travel and it wouldn’t be crazy for me to end up somewhere

So 120 on a rental vac sander, Dawn and hose?
How far do I have to take it down?

120? Geez. It's the bottom of the boat.

I think I used 40 - 80 grit sand paper.

I've completed 3 bottom jobs on my boat and completely removed the paint from the topside hull down to the original Gelcoat and repainted that as well

[SVHarmonie]

Originally Posted by thomm225

120? Geez. It's the bottom of the boat.

I think I used 40 - 80 grit sand paper.

I've completed 3 bottom jobs on my boat and completely removed the paint from the topside hull down to the original Gelcoat and repainted that as well

I agree with Thomm... I NEVER heard of anybody other than a hard core racer doing a boat bottom with 220 or 120. for this job 80 is very fine, 60 is medium, and 40 is coarse.

I have always used 40, and a light hand. Life it is way too short.

Also, the advice that you MUST wet sand is bogus.

A good vacuum sander will work fine. BUT>>>> use whatever the boatyard requires. Some require wet sanding, some vacuum. It all depends on local environmental regs and what the yard can handle. If the yard has no opinion, either works, just don't blow the dust all over your neighbor's boat...

[steve77]

While you are hauled out, it is a great time to operate each seacock and lubricate it.

Cheers!

Steve

[NorthernMac]

How far do I need to take the old bottom paint down?

[Capt Clark]

NorthernMac,

You do not need to remove all the old paint, just scratch it up. You do want to make sure that you are not adding a hard paint on top of an ablative paint.

Nice looking boat! It needs a nice bootstripe.

[Cheechako]

60-80 grit on the bottom. It fills fast and feels more like 120. As said, just break the surface of the old paint.

[Library70]

If the boat is going to be in fresh water, I would check with Interlux before using Micron66 on it. I have heard that fresh water will render 66 useless but don't take my word for it, check with the manufacturer.

[NorthernMac]

Originally Posted by Library70

If the boat is going to be in fresh water, I would check with Interlux before using Micron66 on it. I have heard that fresh water will render 66 useless but don't take my word for it, check with the manufacturer.

Is there a big downgrade for salt ops with the extra vs 66?

I’m guessing I’m going to be mostly salt water, from warm to cold, BUT it is not out of the question for work to have me to end up in a brackish river

[Library70]

I used extra on my power boats for many years and was very happy with it but I've never used 66. I believe 66 is ok in brackish water. Interlux has good customer support, I'd give them a call.