BOAT - SELECTION & REFIT

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The vast majority of production catamarans today are made for the charter market. Until a year ago, I did not fully realize why these boats are NOT bluewater boats. Sure, you could take a Leopard or a Lagoon or a Fontaine Pajot and sail round the world but the majority of the time, you would be sailing in the tropics. Not the Arctic. Not the Antarctic. Temperate climes are dodgy. Even Iceland would be risky. 

Charter boats are open, unprotected, have high windage, have luxury components like hot-tubs and forward cockpits, and are designed with easily replaceable parts because charter people  break them. Things like sacrificial keels that break off when they hit something. Like lower grade winches because they are cheap and easily replaced. Like large cabin sliding doors that are not water-tight or will break in following seas. 

A true blue-water catamaran lowers risk to crew and boat. A true blue-water boat is simple, tidy and tough. A true blue-water boat has these features:

1. SINGLED HANDED CAPABILITY
2. BEACHING CAPABILITY
3. LOW WINDAGE
4. GOOD HELM PROTECTION
5. HULL KEEL & RUDDER PROTECTION
6. SEA PROTECTION - FORWARD, SIDE, AFT
7. THERMAL PROTECTION
8. SPEED
9. SPACE
10. LIVE-ABOARD - It must serve as a live-aboard vessel for some time. 
11. EASE OF MAINTENANCE - The decks and cabins should be easy to clean with vinegar or other natural cleaning products i.e. easily obtainable worldwide. 

Additional discussion items are marked * and include:

ALUMINIUM CONSTRUCTION

DAGGERBOARDS VS STUB KEELS

1. SINGLE-HANDED CAPABILITY - The boat must be rigged for single-handed sailing in case crew become incapacitated or sick. 

All lines should lead to the helm-station or somewhere within arms-reach nearby. 

An autopilot, plus a spare, should be available - on those long days at sea where you stay on the same tack through all kinds of weather, or are single-handing, an autopilot is absolutely essential.

Self-tacking jibs and genoas are very wise and while furling foresails present a jamming risk, lowering the number of instances you have to go forward is a risk mitigation that outweighs this by a wide margin.

2. BEACHING - A blue-water boat should have:

1. A SHALLOW DRAFT - A key advantage of cats over mono-hulls is their shallow draft. 1.5m is common and allows a cat to sail into areas other boats cannot. 
2. AN EVEN WEIGHT DISTRIBUTION ACROSS BOTH KEELS - The stub keels must be capable of handling the load. This will save time and money in shipyards where hoists are either not available or very expensive.

WHY IS BEACHING IMPORTANT?

• You may be located far from the nearest service centre and have to make repairs yourself. 
• You may need to shelter in a hurricane hole, such as a mangrove swamp, with not much draft. 
• You may need to cross a shallow sandbar to access local supplies and good anchorages.
• You may need to enter a coral lagoon to avoid sea-anchoring outside the reef.

You should be able to beach the boat.

The boat should present as low an obstacle as possible to the wind, to prevent being blown off course significantly. Coach roofs with couches are a charter boat hallmark, and lower your solar panel capability too. 

Recently, many charter boat designers have added a lot more windage to their designs, with high flybridges, entertainment areas on the roof etc. For the charter market, sailing through a storm is simply "not a thing".  The blue-water skipper knows otherwise - even with the best weather routing available, storms can come up very rapidly, or come at you from multiple directions. 

And, where Silentstorm is going, avoiding every storm may not be an option. See SPEED below. 

On a blue-water boat...

• The helm(s) should be protected.
• The helm(s) should maximize the watch-captain's vision, with a wind-shield and wipers for rain.
• The helm(s) should minimize instrumentation complexity but still be fully functional - you should be able to plot a new course, add a waypoint, determine battery and water capacity - everything - from the console. 
• The helm should minimise impact on night vision with ALL lighted controls, LEDs etc. adjustable to ensure night-vision is not impacted. 
• The helm(s) should be similar to the bridge on a large ship, with control of all systems enabled there. 

Some shipbuilders prefer dual helm-stations at the stern with an autopilot helm inside for rough weather. This means... 

• You have to run from one side of the boat to the other when tacking or gybing. Not great with a hot cup of coffee or some food in your hands.
• Putting the boat on auto-pilot while you sort yourself out is a safety issue. 
• Viewing through the cabin to the other side may be problematic with guests onboard. Ok, I understand that the windows are big and offer great views. Consider  a rainstorm with rain streaming down all surfaces. I want to be able to see. 
• You need 2 x the instrumentation. A helm-station should be like a large ship bridge, which your ability to control everything on the boat enabled from there. Multiple stations means more wiring, more integration. Yes, your nav-station inside should be a backup, and for really rough weather that is essential. But minimize the complexity. Please. 

One of the things I really liked about the Leopard 45 was the raised helm and hardtop bimini. With a single raised helm...

• A removable windshield with rain wipers is possible and advisable.
• A view of the main and other sails through an overhead window is enabled.
• A 360 degree view of the boat is enabled. True, the forward sails can obscure some of the view at times, but the horizon should still be viewable in all directions, all the time. 
• Sun protection is enabled through a hardtop bimini.
• Note: We will counter the lack of complete visibility due to sails blocking vision by placing a FLIR unit on each bow. 
• The helm can benefit from aft-cockpit heating.

 5. HULL, KEEL & RUDDER PROTECTION - Keels, rudders and bows should be tough and protected, being obviously the parts of the boat that will get into the most trouble most often. Skeg rudders are good, and if you are fond of composites for speed, then a kevlar/carbon mix keel wrap (on the inside) for strength is wise. Ditto for the bow.  If you are going aluminium, and many blue-water boats are, then you will have few worries with pack-ice and dead-heads. 

A blue-water boat should have: 

45CM CLEARANCE - There should be at least 45cm of clearance under the central bridge. 

Less than this, and slamming is inevitable, with waves pounding against the underside of the bridge and creating, at best, loud and uncomfortable boat motion and, at worst, structural damage. Central nacelles (the bit hanging down in the middle on some cats) should be avoided for slamming and for speed reduction reasons. 

Note the picture above - a low bridge and a nacelle underneath. This boat will slam, hard. 

ESCAPE HATCH - An escape hatch in each hull is a good, and a bad thing to have. It is part of most offshore sailing race regulations now, but its incorporation is still controversial. 

An escape hatch provides the following benefits:

• Visibility of issues with the hulls.
• A way to escape the catamaran if it flips. This is HIGHLY unlikely due to the low centre of gravity, but considered a possibility by insurers.
• A medium for photography.

However, it also provides:

• A structural integrity issue in each hull.
• A means for thieves to access your boat in relative secrecy.
• Maintenance of seals and latches.
• Unlocking when leaving for blue waters on every trip, and locking (against intruders) when entering harbour or anchorage.  

Alex Simonis of the Leopard design team Simonis & Voogd had this to say of aluminium construction for mid-sized catamarans (45-50'): "I would strongly advise not to consider aluminium. It’s a great material and I have designed quite a number of yachts in it (all monohulls). I don’t consider it suitable for a catamaran for a number of reasons. 

One being the weight penalty which is considerable in the size we are talking about (i.e. 45' to 50'. I believe it only starts being a consideration when you approach the 70' size and even for that size the goalpost moves up all the time as composites are improving non stop). 

Secondly, the inherent construction method needed for an aluminium alloy yacht is to have frames at reasonable intervals (for a 45-50' boat it would be between 2' and 3') which support longitudinal stringers at a spacing of around 8“. The minimum height for such frames is likely in the region of 4” in the topsides and 3” to 3.25” as a minimum in the deck. On any monohull this is not such a big issue as the hull is wide and deep losing 4” to 5” on each side can easily be accommodated (alloy construction + interior panelling which in most cases is just fitted inside the frame depth and not beyond it as it gets too complex and costly). But on a catamaran with its narrow hulls you lose way too much on the useable width in the hulls and to a degree on the height as well. 

In numbers your 45-50' cat can’t have a waterline beam for the individual hulls going beyond 4' 11” otherwise it is going to get too fat and sluggish. The width we lose in construction going for a GRP cored hull is around 1”3/18 to 1” ¼  on the skin. 2x (each side of the hull) that is about 2.5”  leaving us with 4’ 8.5” of useable floor width. Going in (aluminium) alloy, the hull has the same width limitation but now we losing 10”  (4” for the frame, 1” for the cladding”) 2x for each side. This reduces our effective useable width to 4’ 1”. That might not sound too bad but going forward into the hull it stops the accommodation you can fit by a good couple of feet (3-4' at least).

Last but not least, you need to take good care of electrolysis, your painting needs regular maintenance and if you don’t have 100% full thermal insulation between the hull and the interior it is as wet as a shower."  

Daggerboards may be fast, and can usually be rotated to allow greater pointing into the wind, but that rotate-ability means they can get stuck, and a stuck daggerboard is very, very dangerous. Daggerboards are also easily broken. You will need to carry spares and know how to replace them. 

Permanent stub keels will prevent slide-slippage adequately, are less likely to be broken, and are more easily fixable: simply beach or haul the boat, and then get your glass- or aluminium-patch kit out.   

The forward trampolines should be large, permit seawater to pass through, and drain off effectively. They should provide little or no barrier to the sea, lest a breaking wave submerge them, or a peaking wave punch the boat upward. 

Forward cockpits or hot tubs are not a wise blue-water accessory. Breaking waves over the boat will fill them quickly, adding a significant amount of weight to the boat and potentially causing a pitch forward. Even if the drainage from this area is good, it will not be fast enough to prevent a catastrophe. 

One of Leopard's customers made a video of the boat and asked about this door and the forward cockpit area. A Leopard delivery captain admitted to seawater ingress through saloon door via the door's "watertight" gasket. It is inevitable in rough seas. Best just avoid altogether. 

Similarly to following seas, a swell approaching from either side can provide difficulties for the boat. 

If your dual helms are exposed, expect them to be pummelled, even if you have canvas coverings. 

In addition, your large, exposed side windows should provide a slope to the crashing wave, instead of significant existence. Most charter boats have vertical windows now, which greatly inhibits heat ingress into the main saloon, but which also provides significant barrier to a side sea. 

Some slope is wise - too much, and you will bake the saloon. Too little, and you may see a window cave in.  

A key blue-water requirement is protection from following seas. Most charter boats have large and very open aft cockpits to enable cruiser parties etc. However, in high swells (10m+; short periods), following seas can crash right into the aft cockpit and swamp the main saloon too. 

A truly watertight saloon door and an aft bulwark in the shape, for example, of a lounge seat extending the width of the aft cockpit will assist in diverting the wave harmlessly. This is a topic frequently raised in blue-water catamaran design forums.  

A good blue-water boat will have insulation. This is again a key difference between blue-water and charter boats. Charter boats will have massive Aircon systems. 

A blue-water boat is designed to minimize heat and cold ingress. 

• HEAT - Shades for all windows, insulation and good ventilation via dorades or air-vented hatches are wise. 

• COLD - Again, significant insulation but also protection against condensation would be wise. 

Silentstorm must be fast under sail and under electric propulsion.

Our voyage plan involves a transit of the Southern Ocean. In the Southern Ocean, storms rotate continuously around the South Pole. With no barrier or obstacle, there is nothing to stop them doing so. 

These storms travel approximately 3-6 days apart. In between, there are periods of extreme calm with no wind whatsoever. There is also almost continuous cloud cover. 

This means we will either have no wind (and little sun) or far too much wind. Many boats conducting a transit of the Drake Passage try to do so on the back of a low-pressure storm. Some are successful...

This means a quick transit of these waters during a calm is required. However, wind and hydro regeneration we have to assume will not be the primary energy regeneration sources. Solar regeneration will be limited. So either we will have enough battery power to transit in one run, or we have to have a backup. 

We are still investigating this matter...

Blue-water boats need lots of space, far more than a charter boat. 

HEIGHT - There must be sufficient height inside for tall people (6'6" at least). For us, this is a safety issue. I am very tired of whacking my head on low cabin doorways. 

STORAGE - Lots of storage must be available, for spares, water and batteries. 

WATER - Ensure you can carry 1000 gallons plus a good water-maker (e.g. Spectra).

EASY PASSAGE AROUND THE SIDES - In rough whether, easy passage around the sides is required, with good handholds between waist and chest height.