On a semi displacement barnacle fouled hull, how much slower?

[sdowney717]

Originally Posted by SoWhat

You might think about changing your haul out schedule to every 3 years, or hire a diver to replace the zincs.

You probably won't notice any disintegration or pink color until you close a through hull and it snaps off in your hand. Hope your wooden plugs are handy.

I haul every year and each spring I replace anodes. I use fine grit sandpaper on all through hulls until I have shiny bronze. Slightest hint of pink, out they come. Last few years I have replaced one through hull and 2 raw water intake screens. Once I'm done, I empty a spray can of bottom paint up into the through hulls.

I pulled them all in 2014.
Most are from 1970.
They were perfect.
I don't have any wooden plugs, I do have rags and towels. They are all easy to get to.

In 2006, I did have to repair a bronze shaft log, had worn a lot from rubbing shaft.
It was close like 1/16 inch to breaking thru.
I silver braised and brass welded it with my torch.
Otherwise, was like new. I also coated it with Permaflex polyurethane inside and outside.

This stuff is pretty good but not perfect.
http://sanitred.com/permaflex-waterp...g-description/

[koliver]

Originally Posted by sdowney717

Yes, no problem with that in Va.
What we need is car washes designed for boats!
Drive the boat in and comes out clean other end.
This would make lot's of people happy, like environmentalist that hate bottom paint and boat owners that hate paying for it, and think of the fuel savings, less fuel burned means more money for you to spend elsewhere, plus less pollution into the air.

My idea is the entire process could be automated using 'AI' computers and underwater cleaning machines.

I have seen some automated hull cleaner videos on youtube.

SeaRobotics Delivers Autonomous Hull Cleaning System | News

Of course new tech like this right now is expensive, with time that may change.

In my Sailboat racing days, (90s) every boat was scrubbed before every race. The tool of choice was a home built brush on a long, curved handle, designed to reach to the keel/hull connection and all the way to the bottom of the keel. A full scrub of the 36' boat we raced took about 20 minutes.
That didn't eliminate haulouts, as there were still zincs to be managed and the bottom paint to be renewed, sanded, faired, smooth paint surface petted to coax a 10th of a knot more.

[Greg S]

[QUOTE="sdowney717;519642"]I know a planning hull a lot slower than semi or full.
I would think a full displacement which already moves more slowly, it won't have as much affect as a planing hull but still noticeable. End Quote.[QUOTE]

From the west coast.

A few short years ago I set out on what I thought would be a long one-day cruise to move a 60 foot sailboat for a broker. That one day stretched to 4 very long days. My buddy and I refer to that as our trip from h3!!. Why? Almost entirely due to growth on the hull. What should have been 7 knots at cruise turned into 2.5 to 3 knots. My memory recalls a lot more of 2 and 2.5 than it does 3. If we hadn't been able to maximize our currents it might have been another day again. To complicate matters there was growth on the raw water strainer/ through hull preventing full engine load. Even short bursts of full throttle didn't increase our speed but did increase engine temperature.

I'm amazed you would"plan" for a four year cycle. In our waters conscientious boaters haul every year despite having paint that the manufacturer claims will last two. Some haul outs only last an hour and never come off the lift before relaunch but at least they've done their due diligence, changed zinc's, knocked growth off, touched up paint and checked underwater fittings, shaft, prop and such.

[Bacchus]

Originally Posted by sdowney717

Anyone have observations they can share?

.

Following was from my sea trial experience at purchase... MS 34HT is a SD hull

Boat reached spec WOT of 3300 RPM for a Yanmar 6LYA-STP but top speed was 17 MPH vs 20 MPH spec for the boat. When hauled for inspection hull had about 1" of "Fuzzy" growth from about 2 yrs in warm fresh water w/o cleaning.

Cleaning & new bottom paint restored the 20 MPH speed at 3300 RPM WOT/

[twistedtree]

Originally Posted by sdowney717

Yes, no problem with that in Va.
What we need is car washes designed for boats!
Drive the boat in and comes out clean other end.
This would make lot's of people happy, like environmentalist that hate bottom paint and boat owners that hate paying for it, and think of the fuel savings, less fuel burned means more money for you to spend elsewhere, plus less pollution into the air.

My idea is the entire process could be automated using 'AI' computers and underwater cleaning machines.

I have seen some automated hull cleaner videos on youtube.

SeaRobotics Delivers Autonomous Hull Cleaning System | News

Of course new tech like this right now is expensive, with time that may change.

That exists today. It's called a "diver".

[markpierce]

An annual haul-out and bottom treatment has kept my boat free from poor boat performance due to vegetable and animal growth.

[jimL]

We just had our Mainship trawler hauled in CT on Long Island Sound - first season in salt water. I had zincs on the prop shafts and trim tabs as well as on the transom. The prop shaft zincs are gone, and the trim tabs are 50% or more dissolved as is the transom zinc plate. The propellers, struts and rudders have a very light coating of white pimples - presumeably corrosion. Can I use a drill with a wire brush to remove the very small white pimples? I plan to take the props off to deal with them over the winter.

Next season I'll triple the zincs. In our former marina we suspect our port neighbor had leakage - the port trim tab zinc was noticeably more dissolved than the starboard trim tab.

The bottom paint held up well and the boatyard (Crockers at New London) did an outstanding job in power washing the marine salad off the hull and gear.

Thanks,
Jim

[Comodave]

I would not use a wire brush that is steel, it will leave tiny particles of steel embedded in whatever you are cleaning. Maybe a sanding wheel on a drill?

[Maerin]

No wire brush. Use a scotchbrite wheel. I use it with a 4-1/2" side grinder. No appreciable metal loss, surface cleans up paint-ready. Quick.

[jimL]

Thanks Steve and BoatNut, no steel wire brush? Wouldn't the steel filaments eventually rust and dissolve? Would the hurt the bronze rudder and running gear?

Jim

[Comodave]

The problem is that they will cause corrosion where the small steel particles get embedded. Do you really want a 4 or 5 thousand prop getting damaged due to a wire brushing?

[Lepke]

To repeat everyone else, if the zincs are gone you're eating the surface of the shafts and props. Eventually you'll be able to break a piece of prop blade off with your fingers. I use to do that when I surveyed poorly maintained boats. If you travel at slow speeds, put more zincs on the shaft, maybe a prop nut zinc. A yearly diver is actually cheaper than new shafts and props. Buy a dry suit and a hookah rig.
Or find a marina in fresh water.

[Cigatoo]

Originally Posted by jimL

We just had our Mainship trawler hauled in CT on Long Island Sound - first season in salt water. I had zincs on the prop shafts and trim tabs as well as on the transom. The prop shaft zincs are gone, and the trim tabs are 50% or more dissolved as is the transom zinc plate. The propellers, struts and rudders have a very light coating of white pimples - presumeably corrosion. Can I use a drill with a wire brush to remove the very small white pimples? I plan to take the props off to deal with them over the winter.

Next season I'll triple the zincs. In our former marina we suspect our port neighbor had leakage - the port trim tab zinc was noticeably more dissolved than the starboard trim tab.

The bottom paint held up well and the boatyard (Crockers at New London) did an outstanding job in power washing the marine salad off the hull and gear.

Thanks,
Jim

Don’t overthink this. Your zincs are doing their job. If they are completely devolved they need to be replaced. However your prop shafts and props won’t devolve overnight. I have had zincs last multiple seasons and then only 1/2 of a season due to changes in local boats, being at a different dock, or who knows what. Make sure that you have no wires hanging in your bilge water. A very common problem that will cause your zincs to disappear quickly. Having a few ot more barnacles on the running gear at end of season is also very normal. On and Off hull cleaner (available up the street at Defender) will dissolve them. Use it on the running gear, props, shafts, and the hull to clean the slime. Chip any remaining barnacles off with a putty knife. Replace all zincs and keep an eye on them next year. A diver can do this for you or you can take a quick swim to inspect halfway through the season. If in doubt talk with someone at Crocker’s. Very knowledgeable people there. They can check the bonding or find someone who will if you feel the need to. (I would start with fresh zincs and wait another season) Everything you have described is completely normal. Welcome to crowded marinas and salt water in New England.

[psneeld]

Originally Posted by jimL

Thanks Steve and BoatNut, no steel wire brush? Wouldn't the steel filaments eventually rust and dissolve? Would the hurt the bronze rudder and running gear?

Jim

I would love to see literature saying wire brushes cause or could cause damage.


I have used one for 50 years, and so has every marine business I have worked for and also the marinas I have worked/stayed in.


Maybe it's possible...but I have not seen it so I would be curious as to their harm.

[Cigatoo]

Originally Posted by psneeld

I would love to see literature saying wire brushes cause or could cause damage.


I have used one for 50 years, and so has every marine business I have worked for and also the marinas I have worked/stayed in.


Maybe it's possible...but I have not seen it so I would be curious as to their harm.

I have wire brushed my props for years.

[Cigatoo]

No wire brushes or steel wool on deck as they will make a rusty mess.

[rslifkin]

Instead of wire brushes, I'm a big fan of a wire cup in a drill. They don't shoot pieces out like a regular wire wheel and it makes for a very quick, easy cleanup of parts even when they're kinda weirdly shaped.

I did just order some brass ones for prop cleaning to see how well they work. If they work well, it should have less risk of any corrosion issues.

[psneeld]

Sure there are many variations on wire wheels....


Cleaning an 18 inch wheel is different than cleaning a 48 inch wheel in terms of how aggressive you can go.


If there was one shred of evidence to use brass over steel I would switch..just haven't seen any yet.


And a good steel wheel, brush, cup, etc...is usually a bit stiffer and quicker to clean than brass. And like any tool has to be used judiciously not to damage what you are cleaning.

[Group9]

I was on a 42 foot sailboat that we couldn't get to go over 3.5 knots on the way to the yard. I figured it was going to look like a reef when we pulled it out. I was shocked to see that it didn't take nearly as many barnacles as I would have imagined, to slow it down that much.

They affect the prop efficiency a lot as well.

[rslifkin]

Originally Posted by Group9

I was on a 42 foot sailboat that we couldn't get to go over 3.5 knots on the way to the yard. I figured it was going to look like a reef when we pulled it out. I was shocked to see that it didn't take nearly as many barnacles as I would have imagined, to slow it down that much.

They affect the prop efficiency a lot as well.

That last bit is the key. A little bit of growth in the wrong place can have as much effect as 10 times the growth somewhere else on the boat.