by Kirk Hathaway

 

Given time, most boat owners become specialists on their vessels, whether through investigative pursuit or necessary trial and error.  Embarrassingly, I had owned my sailboat nearly six month before a fellow boat owner informed me of the need for sacrificial zincs on most crafts.  Naturally, such confession amuses my customers; for, as their diver over the last three years, I am responsible not only to ensure zinc protection but also to inform them of numerous situations below the waterline calling for attention.  AND with over 300 vessels cared for in 2010, a number of issues frequently surface calling for attention below the waterline. So, whether as a primer for new boat owners or a welcomed checklist for seasoned boaters, this list of issues might help you keep on top of things and your craft riding high.

 

Issue 1 - Boot Stripe: A boot stripe at the waterline is attractive for a newly splashed boat.  However, relatively soon, a waterline boot stripe becomes covered with wet and then dried algae, often baking on in still, heated waters of the southeast.  Also, as most vessels list (often to a side heavy with tanks, batteries, and tools), boot stripes end up underwater and are the first to exhibit paint blistering and quick, heavy growth of algae and barnacles.  Stern regions most prone to this are difficult to spot from the dock owing to the inward curve of the craft.

 

Dive Care:  Boot Stripes attacked by algae and/or barnacles take up a considerable cleaning time and if your diver doesn’t take care, a painted stripe can end up badly scratched and fogged and a tape stripe will peel away even more quickly than it does anyway.  The use of a nylon brush and the softer 3M pads protect the vessel from harsh scratches while cleaning the waterline.

 

Owner Care: Redistributing weight can help.  While docked or underway, consider keeping your spare anchor and chain outer midship opposite to the side that is listing: often the side with large, filled tanks or batteries. Canned goods and gear stored opposite of galley weight and refrigerator often help balance the craft.  The bottom line is to move weight midship to lift a waterline from one side or from stern or bow. Additionally, brushing down the sides with a long handled deck brush frequently will save both repairs and dive charges.

 

Haul Out Care:  Consider raising bottom paint by as much as three inches. Sure, this will cut into your current boot stripe, but bottom paint as a visual boot stripe will remain cleaner and be easier to brush down over the railing or from off the dock.  If you are thinking, “I don’t want a black boot stripe,” consider that vessels docked in most brackish or fresh water marinas on the southeastern seaboard will quickly find a blackened film of drying algae difficult to clean without a diver.  Rather than having a clean black line, you could easily have an uneven blackened smudge for a waterline.  Besides, not all bottom paints are black, which itself is a consideration for the aesthetic look of your craft on the water and healing considerably.

 

 

Issue 2 – Running Gear:  Those in-the-sling photos of polished shafts, props, rudders of bronze, stainless, and even plastic composites are impressive to fellow boaters.  But consider: unpainted surfaces below the water soon become artificial reefs for marine life.  In North Carolina’s Neuse and Trent Rivers, for example, rising water temperatures from May through September bring seasons of growth from barnacles to algae to river muscles to a spongy moss at the end of the summer and even a tubular worm coral in the later fall in more brackish waters.  Props that might be compared to thin ceiling fan blades when splashed can in less than three weeks of peak summer water become more the rounded light-bulbs within those fans and will provide you nothing for hull speed.

 

Dive Care:  Consider seasonal brush down dives in low growth periods between October and May.  This keeps young, small barnacles brushed off easily with the mere sweep of a sponge.  As waters warm, attached barnacles grow quickly and decrease prop speed weekly; maintenance dives may be required every three to six weeks depending on your waters.

 

Owner Care: When onboard, start engines and engage running gear frequently. If anchored out in warm and relatively clean water, consider snorkeling on your craft and brushing off your prop with a putty knife and sponge.  Don’t take swimming risks if holding your breath isn’t second nature too you.  But if it is, know the best clear water in your area.  In North Carolina, with visibility at inches to feet in most areas, the waters Cape Lookout are one of the few reliable locations for clear water self-cleaning and inspections.

 

Haul Out:  Boaters spend a lot of money on prop coatings to keep marine life off metal surfaces.  However, poor applications often give those coating a limited lifetime of effectiveness.  Some boaters swear by India ink application, which do seem effective for a few months.  Others coat blades, shafts, and rudder with their bottom paint, often resulting in large flaking of the paint or wrinkling (if surfaces aren’t primed properly for metals); however, for one or two seasons bottom paint is often as effective as more expensive coatings.  Considering cost and effort, it may be more reasonable to budget for regular maintenance dives, and the assurance that your running gear and hull remain smooth for departures through the year.

 

Issue 3 - Intakes and Thru-Hull:  Like with running gear, barnacles and algae can quickly block unpainted intakes, and thru-hulls.  Pinhole grates for ACs or generators get clogged easily in late summer growth with barnacles, algae, and spongy moss.  Intakes painted with bottom paints fair better, but with paint applied too thickly, pinhole grates are often closed by the paint nd make growth obstruction even more problematic.

 

Dive Care:  Cleaning by a diver who knows your particular hull better ensures one or two of your thru-hulls doesn’t get missed.  Letting your diver know their specific location helps, as well.  Mostly, though regularly cleaning permits small, new shell growth to be released by hand, brush, or even plastic blades without much effort. Left alone growth migrates both up into thru-hulls and beyond their outer ring, usually destroying surrounding bottom paint as barnacles mature and fasten into paints more than a year old.

 

Owner Care:  Use all your thru-hulls on the boat frequently.  With sinks, consider an occasional flush with a bleach solution.  Clean sea strainers regularly for thru-hulls where water flow may be slowed by clogged filters.  Keep sea cocks closed on engine and other non-operational intakes, but open and flow water through these whenever possible.

 

Haul Out:  The advantages of painted thru-hulls and intake grates cannot be overstated. Painted surface don’t attract barnacle growth as quickly as those unpainted, so if it is good enough for the hull, it’s even better for operational thru-hulls.  Paint more than just the rings.   Get up inside with a brush as far as you can.  And when painting, brush at least two coats of bottom paint around each thru-hull in a circular pattern and then go over this with a roller as the entire hull is being painted, sort of a bandage method.  In this way, areas most susceptible to growth are best protected, and flaking or breaking away of paint from poor roller application around a thru-hull is avoided.  If any thru-hulls need to be changed, consider larger rather than smaller thru-hulls as single bivalves easily and often block smaller holes.

 

Issue 4 – Bottom Paints:  New bottom paint provides protection from growth of algae, barnacles and other marine life, but only to a point.  In time, it wears and growth comes on regardless of how expensive the paint or how protective the water.  Also, bottom paints that are effective in some waters can actually attract growth in others.

 

Dive Care:  Frequent cleaning protects a vessel better than any bottom paint application.  Monthly during warmer growing season (sometimes less) and at least once in every other season allows thin layers of algae and tiny, fragile barnacles to come away with little disturbance to bottom paint.  Using divers with regular contract services or those charging by time rather than foot can justify a more frequent cleaning at lower fees.

 

Owner Care:  Frequent use of your vessel is the best protection against growth.  The cliché “a rolling stone gathers no moss” hold true equally underwater where a voyaging vessel keeps algae away.  Dockside, your deck brush can be the best advocate for a clean hull as growth often begins at the waterline, so sweeping down along the hull into the water and spraying and rinsing the craft frequently will retard growth where it is most likely to start.

 

Haul Out Care: Raising the bottom paint (as mentioned previous) is the first means of slowing growth on the hull.  The other is to know the waters where your boat is home-ported and carefully considers the best paints for those waters.  Some boaters swear by cayenne pepper added to the paint in portions that can be found on discussion boards.  Others debate using or ablative or hard paints.  For divers, hard paints are easier to clean and seem to last longer.  However, older hard paints can begin to chip, and with future paints, just rolled over these areas, this often results in large areas flaking away.  Flaking, too, can be seen in any application of bottom paint if surfaces are not primed properly.  Ablative paints are designed to wear away and for shells to fall away with a thin layer of paint during movement of the craft.  However, many sailboats don’t reach the hull speed required to blow off these barnacles. Also, as ablative paints wears first along the waterline and on the most vertical, forward portions of the bow with lapping and pounding seas, these thinning areas become prone to heavy algae growth and clustered barnacles which become firmly fastened to a thinned out paint and often thick clusters end up directly against fiberglass.  A spray mister with muriatic acid is effective in casing removal while hauled out, but underwater, the best that can often be done in these situations is just to break off the newest barnacle growth leaving a widening patch of barnacle casings until haul out.

Issue 5 – Prop Performance:  Blade numbers, size, pitch, and design justify books written on propeller performance, but underway, propeller operations are sometimes less than desirable and divers called in are asked to inspect and change props, often to the dissatisfaction of the owners.

 

Dive Care:  Poor prop performance is most likely due to a shelled up prop, a vibrating shaft from a very loose cutlass bearing, obstructions of line or net wrapped in the prop or blocking water flow, bent props, and broken parts on movable props. Loose props are sometimes the cause of vibration and can be easily blocked and tightened.  In some cases, a moveable prop can also be made useless by the wrong sized zinc being added on.  Some of these issues can be easily addressed by your diver.  Others can be very costly to repair while in the water, so always balance the cost of repair or replacement with other tasks that might be accomplished while hauling the vessel.  This is especially true if removing a prop also means removing line cutters. By the time a prop has been pulled and replaced, the owner may have paid for a haul out. However, keeping prop clear of shells allows for the best performance and engine RPM.  Simply a cleaning that has been neglected too long usually solves low performance of a vessel

 

Owner Care:  Frequent operation of your vessel ensures that you know how it operates, and if RPM are gradually dropping you can be somewhat confident that you have waited too long for a cleaning and shells have built up.  Keeping zincs on a craft will save you from a blade snapping off when electrolysis had wasted its integrity.  Also, a line cutter of some sort will seriously cut down on obstructing crab pot lines or fishing lines slowing or seizing your engine.  But the bottom line is mere being attentive to waters and instruments while underway.

 

 

Haul Out Care:  Whether a prop is pulled under water or out, it shouldn’t be replaced without careful investigation of design and performance, which means consulting a specialist in nautical engineering. Often boaters move up to better performance props, but without proper matching to hulls and engines, a new prop may not perform any better and in fact may even slow a craft’s movement through the water.  But while the prop is off, the cutlass bearing should be carefully inspected and changed if there is any sign of wear. New zincs can be added to the shaft but make certain they tighten with Alan wrenches as a screwdriver underwater is a more difficult tool to use.

 

Issue 6 – Keel and Rudders:  With forward edge or bottom impact on keels and rudders the keel and rudder are the barometer for shell growth as they require care before any other surfaces on the craft, except maybe unpainted thru-hulls or running gear.

 

Dive Care: Make certain your diver provides you regular information on your leading edges and the bottoms of the rudder and keel.  With bottoming out, paint often is missing here, and barnacles and oyster find these surfaces ideal for growth.  Asking a diver just to clean the running gear ignores the fact that a reef could be growing on the bottom of your craft.  More importantly, with hard run-a-grounds, a diver may be able to inform you of chipping or even cracks that compromise the integrity of the vessel.  If you know you have run-aground, let your next diver know it so he or she can carefully inspect the bottom with a flashlight, check the security of the rudder, and inspect the keel to hull seam to see if the jolt separated paint or fiberglass there.

 

Owner Care:  Staying within channels is a good rule of thumb to avoid such issues.  Another one, though, is knowing that the bottom at your dockage is plenty deep for your craft.  In many cases, new bottom paint can be literally sanded away while in a low water slip it rocks its way into a cradle.

 

Haul Out:  When hauling out, ensure that your vessel is blocked up more than three or four inches.  Too close to the ground makes it impossible to clean off any existing shell casing and to get a roller or brush underneath for painting the bottom of the keel.  Too often, a beautiful bottom paint job is completed with no bottom paint applied to the bottom of the keel, or if it is applied, the application is splashy to say the least.  This is the most vulnerable painted surface of your craft, and it deserves top priority.  It should be cleared completely of shells, primed like all other surfaces, and painted with at least one more layer than the rest of the hull (as should the waterline).  And when it goes up in a sling the areas that have been under blocks need to be painted as well.  Frequently, vessels get dropped in the water and within a week barnacles are forming in two solid bands where wood blocks have been.  And it isn’t long before these bands will expand out from them if not cleaned frequently.

 

Issue 7 – Zinc Care: As the opening indicates, being a boat owner doesn’t mean you automatically know everything about boats.  But the one “must know” from the beginning is boats at dock send or receive or have passing through their metallic surfaces stray electrical currents.  It’s not rare thing for a boat owner to call a diver with concerns of a fowled prop only to discover that a blade on the prop, compromised for too long without protective sacrificial metal, has itself been sacrifice and with one engagement of the transmission has snapped a bladed off the prop hub.  Inspection will show the remaining nub and hub pink and sometimes putty-like: useless.

 

Dive Care: When shafts permit, two zincs rather than just one should be used for zinc protection.  If possible, have their wear staggered so that at any one time there is a zinc near 100% new and another just below 80%.  When a shaft zinc gets to 60% it should be replaced, for at this point, the fastening bolts are exposed to a nut that cannot be tightened further.  And with the bolt fully exposed, it is only a matter of revolutions before it spins off.  Zincs at the end of props go more quickly, so ask your diver to use fastener enamel around on the zinc edges around the bolt holes. True, you don’t want to paint the zinc, but three thin bands of lacquer around the screw edges will ensure the cone of zinc wears further before the zinc spins off. Beneteau zincs being comparatively smaller may need replacing more frequently. Trim tab, rudder, strut, and transom zincs can usually afford to go down to 30% or even 20% as the zincs are not mounted on fast moving parts.

 

Owner Care:  Use a diver who knows “your” boat.  Every boat at every slip burns zincs at a rate different than the craft next to it.  Electrical specialist may find cause, and maybe a galvanic isolator with help, and a grounded zinc hanging over the side will act as a good barometer and also slow the wear of your vessel’s zinc.  Keep record of all your zinc sizes and locations.  Know how many months are between new and wasted zincs on your craft.  This should be a constant and if it changes, then new electrical issues have been introduced whether via your or another craft. 

 

Haul Out:  You may be tempted to replace zincs with heavy-duty zincs thinking they will last twice as long.  In fact, they may last a lot longer.  However, it is not uncommon to find with vessels using heavy-duty zincs that the zincs will have plenty of wear left to them even as pitting is showing electrolysis effects on the shaft.  A zinc is only a few dollars.  Even a couple times a years, it is worth burning away at the risk of retaining a zinc and finding damage to essential metals.  Also, if you replace zinc make certain the one you put on has a grounding copper bead to smash into the stainless for better conductivity, and never use a zinc with a Phillips or standard screw head, only an Alan Wrench head.  Screwdrivers under water do not get near the same torque as an Alan wrench.

 

In the end, the condition of your vessel’s bottom has as much to do with your diver as it does with your options of care and dockages.  Out of the water, there is much you can do to ensure that your bottom paint is most effective after it is launched.  However, where she is docked and the frequency of use are two important factors when concerned of growth and issues of electrolysis.  Whether you prefer a tranquil landscape view from your dock or a historic cityscape, the only way to ensure a particular place is a good location for your vessel is to ask a local diver what growth is like there.  Frequent cleaning will keep a vessel clear and smooth for her next voyage.  However, there should be periods when your vessel needs less work, as well as warmer, growing seasons when she will need more frequent care.   Lastly, consider your diver and dive rates.  Do you get a detailed analysis for your dive?  Does a price per foot dive guarantee any particular time or comprehensiveness toward your vessel?  Possibly, paying by time rather that foot ensures that your vessel is cared for according to her needs.

1. Kirk Hathaway is owner and operator of Bottom TIme Diving and Hull Care.

Cape Carolina Index

News Update: 3/1

Current Dive Info

NAV Station

All Ashore!

Underway

Dockside

Features

Readings

At Anchor

  Ship’s Store

Captain’s Logs

Submitting, About, Ads