Category Archives: Safety

All articles related to safety

What is a Galvanic Isolator?

It’s all about shore power and underwater metal corrosion, for example your sail drive on our Seawind. I struggled with the concept. Why buy a galvanic isolator? A post from Charles Fort was helpful.

When SV Kiskadee is plugged into shore power, it is electrically connected to everyone in the marina via the green wire, the grounding conductor. All boats are part of one galvanic cell.

Galvanic Corrosion

The weakest metals, like your aluminium sail drive and anodes will corrode because there is always current in a galvanic cell. The weakest metals with the most surface will function as a ground connection to earth, for the whole dock.

It’s one electric circuit. So your anodes are also contributing to the corrosion protection for all the other yachts plugged in. Your fresh, unpainted anodes will be sacrificed for all your neighbors.

Galvanic Isolator

To solve this problem there is the galvanic isolator. Its successor is an isolation transformer, more expensive, more weight, electronically monitored, but functional the same. When connected to shore power on a regular basis, you need a galvanic isolator installed in your shore power system.

Look for a marine rating when buying a galvanic isolator. The isolators must be rated for system amperage. If you have a yacht with an older isolator installed, or if you experience at any time a high power surge from shore or lighting or … test your galvanic isolator. Here is a simple instruction with a multi meter.

Corrosion types

Worn anodes are still the primary cause of corrosion on engine, hull, sail drive, propeller and rudder. If anodes seem to be suddenly wasting away, you may be a victim of galvanic corrosion. Shore power and no protected of a galvanic isolator is probably the second common cause of corrosion. Local rusty spots special on stainless steel components are either surface contamination or a leaky, shafted 12v AC wire to a sidelight etc. Also easy tested with a multi meter. Metal corrosion is sometimes hidden or out of sight. Can be prevented with painted coatings, PVC busses, isolating kit or using the same metal.

Metal Corrosion

Chain & Anchors

Actually this story is more about the chain than anchors. And all obervations are infuenced by the weight of your yacht, deep or swallow anchoring, multi hull and a few other parameters.

Take our SW1260, supplied for a circumnavigation, she weighs, all in, about 26.500 lbs or 12.000 kg and is in most tables a 42´ heavy. Calculations and reference tables are done with 30 knots, 7 bft, wind.

LightMediumHeavyChainWeight /m
46’–50′41’–45′37’–40′5/16″ or 8mm
1,4 kg
51’–60′46’–54′41’–48′3/8″ PC/BBB ~
10 mm grade30
or 5/16″ G4
~ 8mm grade43
2,1 kg
1,4 kg
Diameter of chain based on the 1/16¨ per 10´ or 9´ or 8´ length rule
( Light, Medium, Heavy)

Maxwell HRC8 Windlasses

The standard windlass is a Maxwell HRC8 which is able to handle 5/16″ BB, 5/16″ ISO G4, 8mm DIN 766, 8mm ISO 4565. For 10mm, 3/8¨ chain a H10-model is necessary.

Chain Length and Grade

Oké let’s start with the basics, old fashion is a 7 to 1 ratio on chain length to depth. With modern anchors, it’s 3 to 1 for calm and or swallow anchoring up to 5 to 1 for a rougher, deeper anchoring, is oké. So the upgrade from Seawind to 80 mtr is on a lower limit. I prefer 100 meters of chain.

RVS chain
Example of a chain, 8 mm RVS (318) grade 60, beautiful, strong and expensive

I think that the standard chain Seawind offers is Grade L aka PC/BBB/grade30 and again on the lower limit. In my opinion grade43 should be the standard and I prefer grade70. See the table for strength and weight and prices. (In Holland, prices in Q1 2022)

grade (8 mm)WLL in kgBLL in kggewicht kg/m€/m (ex VAT)
308203250 1,48,47
4312004400 1,47,77 – 9,83
70320070001,49,87 – 20,50
(RVS 316)
300062001,437 – 40
30 (10 mm)127551002,311,61
WLL = Working Load Limit, BLL = Breaking Load Limit

So my strategy is upgrading to the Seawind option of 80 mtr standard chain. It will last a year. Afterwards I would order 100 mtr (DIN 766, Ø 8 x 24 mm) chain grade 70 or 43. Far stronger and enough length for my sailing area, the Pacific. Buying a 8 mm higher grade chain is always less expensive than upgrading to a HCR10 Maxwell and 10 mm chain, grade 43.


Modern plow or scoop anchors (Excel, Delta, Spade, Mantus, Manson perform well compared to an older plow like CQR or a claw anchor like a Bruce or a Danforth anchor like a Fortress.

I would strongly advise to upgrade from the standard 45 lb CQR anchor to a 48 lb Sarca Excel No 5 galvanised anchor. The Excel anchor is well known for its good initial setting on a relatively short chain and its holding power. The big question is what is the right size anchor, I find this article on the UK site of Jim Green helpful.

LOA (mtr)10-1212-1515-17
Weight (ton)3,5-77-1515-21
Sarca weight (kg/lb)16/3522/4830/66
Sarca type456
Sarca Excel Supplier Recommendations

I am comfortable with the Sarca Excel #5 and find it a balanced solution with a Maxwell HCR8 windlass and a 8 mm chain, grade 43.

We opted for the secondary anchor, a nice 35 lb Delta to be used as stern, tandem or temporary anchor.

Other important stuff

Buy an anchor swivel, always a pleasure to position the anchor on the bow roller. Most swivels attach directly to the anchor, using a bit of blue lock-tide. On 8 mm chain you use a 10 mm swivel. Almost all modern swivels like Mantus, Ultra, Lewmar are stainless steel and corrode your anchor and chain. Swivels are expensive. Rex Francis, designer of the Sarca Excel is not a fan of swivels because of lesser resetting of the anchor and lateral forces breaks swivels. Something to think about.

Buy the Anchor Bridle, it´s not an option. To release the tension of the chain from the windlass, you need an anchor bridle. I prefer nylon double braided because of its quality to stretch and flex.

Length indicators, 1 white tie wrap = 10 mtr of chain, 2 tie wraps etc. Or buy any fancy indicator.

Have a 8 and a 10 mm high quality Bow shackle with you. Always handy when something brakes. I also like a Kong Stainless Steel Universal Chain Lock

And I always carry a spare chain hook. A RVS hook will get bent and forged one breaks.

Taking on water

I read an advertorial on on pump capacity and because Google is smart it serves my an article on a sailing crew fighting to keep up with the incoming amount of water after a collision with a whale or container or refrigerator. Which made me added 2 essential parts on my safety list on preparing our Seawind 1260 for an circumnavigation.

Bilge pump real capacity

Interesting article with one picture saying it all. In a normal situation you will lose ~50-70% of the advertised capacity of a bilge pump. 70% of 2.000 litre per hour ( ~510 gph) is a 10 ltr bucket per minute. Alternatives are water intake of your engine, 70-100 litres per minute and the manual bilge pump at a max of 50 litres per minute.

It will handle a leak on your water system, rain, sea or bow water in heavy conditions. But it is a false feeling of safety to think it will keep you afloat.

Real capacity versus advertised

Industrial Sewage Pump

Part of the problem is the use of 12 volt DC. You need a lot of ampere to obtain a higher wattage. So switching to 230 volt AC is a first step. Second step is you need a more industrial design to pump a higher volume. So after looking around I opted for a sewage pump of Vevor, heavy duty, big hose etc. You need electricity, at least one engine running and your converter higher up, not in the engine room.

Vevor 200 litre per minute 230 volt, 500 watt pump
Vevor 200 litre per minute 230 volt, 500 watt pump

Anti-leak agent

Everybody odd to have conic wooden plugs for an broken valve or hull transit. But for a real crash or a rip that is useless. A lot of stories and experiments on other solutions. Remarkable good is stuffing a pillow into the crash hole securing it with wooden beams etc. In a closed bow compartment stuffing in fenders, classic cork life jackets etc to suppress the water and obtain bouncy, also works. For larger cracks a sail outside the hull, but it is difficult to deploy and to keep it in the right place. And of course there is fiberglass and epoxy.

Composite Patch from aplTec
Composite Patch

A Spanish company, aplTec, took that idea to the next level and developed a product called Composite Patch, a easy to deploy fiberglass sticker to repair survives, even underwater. It´s around now for a decade and seems to work quit well. The shelf life is 18 months.