Global Surveyor – Aleutian 70 Design

Vessel









Global Surveyor is a fully certified Ocean Going Charter Vessel. She was specifically designed to sail safely, comfortably, and without worry to all parts of the globe She is very strongly built, which gives a tremendous feeling of security and confidence. The size, displacement, and design give masses of room aboard, and a steady comfortable motion. She can make fast passages and requires only a modest effort to sail. This is a pleasure cruise, and while the vessel will be sailed to a high standard of seamanship, there will be the minimum of shouting, rushing about, and being soaked by icy waters.
Skipper










The skipper has had a lifetime of worldwide seagoing experience including 14 years in the Merchant Navy, typically on 30,000 tonne cargo liners and tankers. As a Marine Consultant concerned with oil spill control, having direct authority over fleets of Naval and Commercial vessels on manoeuvres. He has also direct handling experience with many types of vessels including Rig supply vessels, tugs, hovercraft, fast patrol craft and sailing vessels. He obtained a Masters Certificate Foreign Going certificate in the MN, and now holds a commercial RYA Yacht master Ocean certificate. At least one other experienced yachtsman will also be aboard
Self Build









Global Surveyor was designed in conjunction with a naval architect, and built with the help of two welders. It was constructed from 20 tonnes of steel piece parts. All were cut to +- 1mm which ensured easy, quick, accurate and trouble free construction to a high standard. 

Amazingly enough, the cost of building an Aleutian 70, like Global Surveyor is roughly the same as buying a typical new 40 foot yacht. This value is also put into perspective when you consider that new yachts of Global Surveyors size can cost up to 4 times more.
Design Concept











For a safe, comfortable and fast passage maker, with the ability to routinely and with peace of mind sail to all parts of the globe from the tropics to the edge of pack ice.
Capable of being easily sailed by a crew of two, while having berths for a potential fourteen.
To have four equal status double cabins for possible charter.
To have an excellent load carrying capability (5 tonnes) to enable the mounting of diving and scientific expeditions.
Without any compromise to safety, to produce a vessel that is easy and economical both to build and run.
To produce a vessel with its own distinct ethos. Something that equates to a ‘working vessel’, a ‘little ship’ that can earn its keep, rather than just another pleasure yacht.
CAD Parts






























THE ADVANTAGES OF CAD GENERATED PIECE PARTS:

The hours already spent on the computer, equate to hours saved in construction.
It is easy, at the computer stage, to modify various aspects within the basic hull form. For instance, superstructure, cockpit position/size, bulkhead number/position, may be varied to personal requirements.
Once the design has been fixed and ‘proved’ all future kits of parts are easily repeatable.
There is no lofting, transferring of paper plans and cutting. Each operation takes a significant time and carries its own chance of error.
Cutting steel by any means costs money.
The steel is shot blasted and primed. It is submerged plasma cut to prevent distortion and is accurate to +- 1mm. It forms one truck load and is delivered ready for fabrication.
Because the parts are pre-shaped, have built in slots, tabs and locating cuts, construction is easy, foolproof and accurate and can be done by anyone with the necessary welding skills.
The approximate halving of construction time means that it is economic to employ sub-contractors or a shipyard if required, Even for a self builder ‘time is money’
The speed of build also minimises corrosion problems and may obviate the need to shot blast on completion.
At the end of the day, the difference in original cost of a kit of parts, against bare steel parts will represent a very small percentage of the overall investment. The market value of the vessel when sold however will largely depend on the integrity and finish of the hull.
Size





























































































































THE ADVANTAGES OF A LARGER VESSEL:

What is the best size for a cruising vessel?  

Minimum size
This perhaps depends on the numbers that need to be carried. 

A reasonable minimum for ocean cruising might be LOA in meters = 9 + Number of persons on board 

Efficiency
A larger vessel than this minimum will be able to sail faster and keep going through a greater range of conditions. It will therefore be a more efficient tool for long distance sailing. It will also be more independent, being able to carry a greater amount of stores, water and fuel.  

Safety
A larger vessel will be safer. It can be more strongly built. The thicker shell plating and number of watertight compartments will better withstand high-speed impact with whales, semi-submerged containers or in port, the loving embrace of a trot of Icelandic fishing vessels. It is also less likely to be capsized in rough weather, more likely to remain watertight, if it is inverted, and will more readily return to the upright. For personal safety higher guardrails can be fitted, which tip the crew back inboard, rather than somersaulting them overboard. 

Comfort
The laws of physics dictate that a larger vessel will not only have more room but will also be more comfortable. Its motion will be slower, and it will roll, pitch, and heave less. Under sail it will have a lower angle of steady heel. It will have greater freeboard leading to drier decks. Crossing the Atlantic I was in touch with a nearby 38′ yacht. The owner was locked below decks being constantly thrown around, and despite still being in his oilskins, completely soaked with water squirting through gaps in the hatch boards. He described the experience as like being in a tumble dryer. Nearby all my crew were lounging on dry decks in bathing costumes, with drinks resting on the decks, and with all the hatches wide open. In the past 38′ has been considered ideal for a couple. While it is true that given a level playing field a larger boat will cost more to purchase, maintain, and moor, adjusting the slope on that field can drastically reduce that difference. 

Purchase Costs
The purchase price of a new vessel will vary as more than the cube of the size. A 60′ yacht will thus cost at least 8 times more than a 30′ one. A simple self-built yacht can cost far less. The steel required for a 60′ yacht may only be £5000 more than for a 30′ one. Purchasing equipment at trade prices can make 30-60% savings. Because there is less competition from other yachtsmen, as-new items can be purchased at up to 80% discount from Boat Jumbles. Similar fiscal creativity can similarly reduce maintenance costs. While it may cost £1000 to lift a large vessel out of the water to antifoul, it may only cost £25 to lean it against a harbour wall. In bulk antifouling paint can cost £5 per litre. 

Mooring Costs
A larger vessel by being self-sufficient with a large seaworthy tender does not need expensive marinas, but can spend most of its time anchored for free. It has often been maintained that a larger vessel is much more difficult and requires more effort to both sail and manoeuvre. 

Handling
A number of light displacement ladies have shown that it is possible for one person to not only adequately sail but also race a relatively heavy displacement vessel. Multiple roller reefing foresails and lazy jacks have greatly reduced the effort required to sail. An electric capstan can not only raise an anchor of any weight, but also can also adjust moorings and hoist sails. The substitution of brute force with seamanship and the main engine can mean that berthing requires no more effort than lifting a rope and placing it over a bollard.. All this is done on a more stable and upright platform, which is also less likely to be suddenly blown sideways when coming alongside.  

THE ADVANTAGES OF A LARGER VESSEL
A simple large yacht, can cost less than a small complicated one. It represents ‘MORE’ Safety, Comfort and Speed.
Other things being equal and when considering the whole range of marine risks a larger vessel is generally more ‘seaworthy’.
Steel is the strongest, most adaptable and economic materials for hull construction. It is the first choice for many experienced blue water sailors. Its strength, workability and longevity is however, a function of plate thickness.
Large size allows the use of thicker plates and the inclusion of watertight bulkheads, without incurring the weight penalty, which would be unavoidable with smaller vessels.
With any number of crew, more internal volume means more live-aboard comfort, shelter, privacy and convenience, combined with less ship motion and heeling.
The vessel is comfortably and safely usable for a greater percentage of time in a greater range of weather conditions.
There is more potential speed available from a longer LWL.
There is therefore greater freedom, to sail further distances in less time and to more reliably return if operating to a timetable.
Where desired, speed can be traded for comfort and convenience. Thus a large cutter, comfortably jogging along under staysail alone, may easily out-perform a smaller yacht under full sail, covered with spray and with its lee rail buried.
The substitution of ‘seamanship’ for brute force, means that a large vessel can be sailed and berthed with no more effort than a small cruiser.
Extra convenience can be purchased if desired, in the form of furling sails, power winches and a bow thruster.
A larger vessel can carry more stores, allowing a greater range of operation, with less dependence on shore side facilities.
Financially a large vessel can, by being more fully utilised, be much more cost effective, than her smaller sister, particularly if syndicate owned.
A larger boat capable of carrying a rigid dinghy can be kept on a cheaper swinging mooring and when cruising expensive marinas are an option, rather than necessity.
Design













































































































































































































MAJOR DESIGN DECISIONS

Length over deck. 19.95m
Safety, Comfort, and speed, generally increase with size. 20m was chosen as the largest that could be easily handled by a crew of two while providing enough room t o sleep a possible 14 and provides exceptional comfort with lesser numbers. 

The deck length was kept just below 20m to minimise possible regulatory impacts. 

Length Water Line. 17.71m.
Maximised to increase internal space, reduce the entry and exit angle of the hull and to give the greatest sailing speed. 

Beam Over all. 5.00m
A moderate beam is utilised to reduce resistance especially to windward and minimise the broaching tendencies of wider hulls. ( Coincidentally 5m is also the maximum that is generally road transportable in the UK ) The waterline beam is maximised to give good initial stability and load carrying without increasing deck weight. This also gives a massive amount of usable room down to sole level in the accommodation. 

Draft. 2.85m
Is sufficient to give a good sailing performance without being unduly deep. The wide keel gives high structural strength and allows the ballast, water and fuel to be carried low. The sump of the engine also fits into the keel. This in turn means a low and continuous sole level throughout the accommodation. The overall effect is to lower the centre of gravity thereby increasing the vessel’s stability both initial and ultimate. 

Freeboard.1.75m Fwd 1.45m Aft
A fully flush deck was chosen for its inherent strength, simplicity and the gift of maximum useable deck space. 

Deck

The windage of the hull and height of the centre of gravity of the deck, mast and rigging, together with the heeling moment of the sails all increase with an increase of freeboard. The low height of the cabin sole allows a moderate to low freeboard to be maintained while still keeping a general 2m (6’06’) of headroom in the accommodation. 

A straight sheer amidships increases the longitudinal strength of the hull and maintains headroom throughout the accommodation. The camber of the deck and bulwark height give sheer to the profile. 

Hull Construction
Radiused chine construction was chosen to give the sea keeping characteristics of round bilge while being economical to build. The Design Water Line is set at a displacement of 52 tonnes thereby including near maximum stores, crew and water, together with a large quantity of personal equipment. Many other vessels are designed to an unrealistic light displacement and spend most of their time overloaded, with a consequent loss of, safety and performance. 

Rudder
The rudder is larger than normal to give better balance under sail and the directional stability of a long keel. A spade rudder was chosen so as to reduce steering loads by being fully balanced and to give a smaller turning circle ahead, and better control at low speeds and when going astern. The rudder is hung on a high strength 12 mm thick steel stock 193.7 mm diameter which provides greater strength than most skegs. 

Wheelhouse / protected cockpit
It is not pleasant to char boil under a tropical sun or be deluged by freezing spray in the North Sea. A wheelhouse is therefore vital both for morale and safety. The dimensions required to give headroom and visibility are fixed by the human form, the wheelhouse could easily have turned into a box. It is suggested that this vessel has an exceptionally nice looking wheelhouse. 

Depending on personal preference all the Navigation and engine instruments, radar etc are within the Wheelhouse, close at hand for the helmsman. 

An inside wheel is not thought necessary as a dodge control could easily be fitted to the autopilot. The position of the wheel at the front end of the open cockpit allows the helmsman maximum uninterrupted vision, keeps him clear of the winch men and gives him maximum shelter. 

The relatively high binnacle and moderate diameter wheel means that crew can easily slide alongside the wheel while the helmsman has the choice of steering from inside the shelter, standing behind the wheel, or sitting alongside. When berthing a step raises the helmsman’s eye level for even better visibility. 

Anchor
140kg genuine CQR. Self-launching and recovery (never needs touching). on 80m of 16mm chain. Not only did this as-new, but surplus anchor cost less than 1/10th of one half the size, but restful nights are assured. 

Bowsprit
Is strong enough to stand vessel vertically on end. Angled lower part to prevent pounding. Increases sail area with a shorter mast. Increases directional stability. Good place to set the cruising chute. Excellent place for the anchor and keeps the chain clear of topsides in wind over tide situation. The enclosed leads are strong enough to shackle moorings eliminating chafe. Best place to watch the dolphins and put the world to rights. 

Forepeak
A fully watertight collision bulkhead to the accommodation is the second line of defence against semi-submerged containers. (the first is 7mm steel plating) Place to stow all the ropes, sails fenders, inflatables and anything else that might be damp, separate from the accommodation. Position for echo-sounder transducer, giving 5m warning of shallow water.  

Capstan
Set well aft to lead the 450kgs of Chain into the forepart of the keel where it is nearer the centre of the vessel for better motion, and low down for stability. As well as controlling the anchor it can be used for adjusting moorings (has pulled the vessel across 200′ of mud), and hoisting sails. 

Deck
The large uncluttered area gives a huge space for relaxing and working the vessel. The deck can also be used to collect drinking water at the rate of 600 litres for every 10mm of rain. 

Accommodation
Fixed berths for 14 persons. All berths are very large and secure with 6′ foam mattresses. The saloon is 5.6m long giving room for 20+ to enjoy cocktails. All the major weights are contained low down within this central section; namely 14 tonnes lead, 4 ½ tonne of fuel and water, and 1 tonne of engine. There are 5 transverse and one longitudinal watertight bulkhead. There is only one seawater inlet, which feeds the engine and loos. The first valve is 150mm above the waterline on a 10mm wall thickness steel standpipe. The water filter is instantly visible and can be quickly cleared if blocked. Domestic discharges all go into a 300litre-holding tank, which can be pumped overboard through an above water fitting. The large centre steel hatch not only allows direct removal of the main engine but can also be left open in following winds of less than force 6 to give a massive amount of light and ventilation into the accommodation.  

Rig
A cutter rig efficiently divides the total area into manageable sizes with good flexibility. It allows the mast to be nearer to the maximum beam of the vessel giving the best staying angle, which increases the security of the whole rig by reducing the loads. 

Deckhouse
Keeps the crew out of the rain, spray and freezing wind in high latitudes and out of the direct impact of a vertical sun in the tropics. Not only is this hugely comfortable, it also massively reduces the risks of hypothermia or sunstroke. It also reduces fatigue and worry, which can adversely affect decision-making. Long term it can help prevent skin cancer. 

Large spade Rudder
Increases directional stability. Will steer the vessel down to 1/20th knot when going ahead. It also gives very positive steering when going astern. Connected to give 50? of helm allows the vessel to turn with a radius of 10m. Its rudderstock of nearly 200mm diameter means it is not going to fall off. 

Self-Steering
This gear steers the vessel effectively in conditions between 5 and 70 knots of apparent wind. allowing single-handed ocean watch keeping.  

Keel
The medium length fin keel is of wide cross section to give massive strength. It also allows the lead to be carried as low as possible with capacity above for 1200 litres of fuel. The width also allows room for the lower part of the engine, which can then be fitted beneath the saloon floor massively increasing the useable space in the accommodation. 

The bottom plate is 25mm thick, which gives piece of mind when navigating by Braille. It also allowed the easy welding of a wing keel, which reduces synchronous rolling by about 40%.
Spec

























SPECIFICATIONS

Length overall – 21.5m (70.5′)
Length on deck – 19.9m ( 65′ )
Beam – 5.0m (16.4′)
Draft – 2.85m (9.3′)
Sail Area – 230 sq m (2,370 sq ft)
Displacement – 45 tonnes
Engine – 130 hp
Fuel capacity – 2100 litres
Range under power – 1800 miles
Water capacity – 2200 litres
Payload – 5000 kg

EQUIPMENT
16-man liferaft
Aluminium and inflatable dinghy
2 tonne capstan
Graphic sounder
Autopilot, electric
Self-steering, wind
VHF/MF/SW/”Satcom”/EPIRB radios
2x GPS
Radar
Wind and solar chargers
Main anchor 140kg CQR, 80m of 16mm chain
2 X Kedge anchors, 50kgs
Living quarters





















































































































































ACCOMMODATION FROM FORWARD
The accommodation is designed to make the absolute maximum use of space within the vessel while avoiding an ‘overcrowded’ look. The engine is completely contained beneath sole level allowing a constant floor level throughout.

Layout Plan 

Forepeak. Length 4m (13′) Stowage of sails, inflatable dinghy, fenders, ropes etc. Large steel deck access hatch.

Watertight Bulkhead.

Crew Cabin or Workshop. Length 2m (6’06’) Can be fitted out to hold up to four crew or to provide a workshop depending on requirements. ocean hatch for light, escape and ventilation.

Watertight bulkhead with Wt door.

Central corridor with ocean hatch, doors to forward guest cabins

2 X Guest Cabins. Length 2.8m (9’01’) Each fitted with either two bunks or a double berth and occasional pipe cot. Deck light and dorade ventilator.

Double berth

Watertight bulkhead with Wt door.

Main Saloon Area. Length 5.6m (18’02’) The saloon was kept as large as possible to give the visual impact of space and to be the main below deck working/relaxing area. At the same time the furniture is arranged to divide up this space below waist height, which together with hand holds provides maximum crew security in heavy weather.

Saloon

On the Starboard side is a large Galley fitted with a crash bar to provide a secure working environment in heavy weather. The cooker is positioned fwd to prevent the crew being thrown against it and is fitted with high fiddles.

Galley

Toilet/Shower compartments are situated Forward and aft of this to provide for the two separate accommodation areas. There is also a wet locker.

On The Port side is the main seating area. The Settee is U shaped to allow comfortable use on either tack, and the table is split to allow easy access.

Aft’ is the Navigation/office space. According to preference most of the active navigation will be conducted in the wheel house but this area provides a quiet office space for tactical planning, and working on ship and other business. With the shelter provided by the wheelhouse it can be safely equipped with Computers, fax and communications equipment.

Dorade ventilator, Deck lights, Ocean Hatches, and a large engine deck hatch, provides ventilation, light and escape routes, together with the easy removal of the engine. There is access through the floor to the engine, and services together with under floor storage. A ladder provides access to the wheelhouse.

Watertight bulkhead with 2 X Wt doors to after cabins which are separated by a longitudinal bulkhead.

2 X Aft Guest Cabins Length. 3.2m (10’05’) fitted with double berths. fitted with ventilators and a clear hatch into wheelhouse for escape and light.

Rear twin

Watertight bulkhead.

After Peak. Length. 2.4m (7’09’) Containing Steering gear, generating set, and bosun/engineering store for fluids. Access through steel deck hatch.


Each individual berth including the mid line of double berths are fitted with lee clothes for use at sea. There is massive stowage space ( 5 cubic meters. 170 cu ft ) beneath the cabin sole alone.

Good ventilation is provided throughout and escape to deck is possible from all watertight compartments.

Hull

















































HULL FORM

The hull is designed for: 

Maximum seaworthiness. With easy lines, an excellent range of stability to 135 degrees, a buoyant rounded transom, moderate beam and maximum structural and watertight integrity even in the event of an inversion. 

Minimum motion. The fine bow and broad stern section together with the concentration of weight amidships ( Lead 14,000 Kgs. Diesel engine 600 Kgs. Fuel 1400 Kgs. Water 2,200 Kgs. Chain 500 Kgs ) minimise pitching while the hard bilge section combined with the heavy mast section gives greater damping and inertia to reduce rolling. 

Good performance. The relatively fine topside sections forward will allow the vessel to cut efficiently to windward while the prismatic coefficient was chosen to give the best efficiency around the most common cruising speed of V/ sqr(LWL) ( 8 Kts ). 

Maximum Load-carrying and internal volume. The relatively hard bilge gives exceptional load-carrying ability without affecting performance and allows the usable accommodation to extend to near the full beam. 

A 1:15 Scale radio control model has been tested and indicates a clean running hull, with excellent directional stability, even under an unbalanced sail plan. The model also exhibits a high degree of roll and pitch damping. 

The capacious hull allows a large range of accommodation possibilities and the design can support any standard of fit out, from the utilitarian to the exotic. Computer generated “Steel Piece Part” construction allows the superstructure, cockpit and bulkheads to be economically rearranged to individual requirements. It would thus be quite simple to have, for instance a twin screw centre cockpit ketch within the basic hull form. 

However the basic ethos of the first vessel is for simplicity, economy and low maintenance combined with rugged seamanlike reliability.

Propulsion

























A non turbo charged medium speed diesel engine of between 80-140 HP is preferred. A Mermaid Marina six cylinder naturally aspirated 135 HP. diesel fitted with a 2.91:1 reduction gearbox and a thirty inch self pitching propeller has been chosen to give economic and reliable propulsion. 

The horizontal shaft line and propeller position in clear water promotes good propulsive efficiency and together with the rudder, excellent manoeuvring both ahead and astern. 

The self pitching propeller maintains good efficiency over a range of conditions from motor sailing, using minimum power with a high pitch, to plugging against a full gale utilising full power and low pitch. 

Feathering will give minimum drag while sailing. 

It is possible for just about any propeller to be fouled by flotsam. The distance between the rudder and propeller minimises the possibility of simultaneously jamming the rudder. 

When operating in ice a cage will be temporarily welded around the propeller. ( another advantage of steel )

Ground Tackle











A 66 Kg main CQR anchor and 80m of 15mm chain has been chosen to provide the main ground tackle. 

The main anchor is housed on the bowsprit giving the best lead for secure anchoring. The kedge is stowed at the stern and drops over a stern roller. 

The electric windlass is situated well aft where its warping capstan can additionally be used for the control of head, spring and stern mooring lines, recovery of the stern anchor and the hoisting of sails. It also allows the 400 Kgs of chain to be stowed within the keel lowering the CG and keeping the weight amidships.

Rig



























The cutter with bowsprit was chosen for this vessel because; 

a. Next to the sloop it is the most aerodynamically efficient. 

b. It gives the most sail area for the minimum mast lengths. This vessel requires a 23.5m mast as a cutter, it would require a 26.5m mast if rigged as a sloop and a 22m main + 15m mizzen = 37m total as a ketch. 

c. There is therefore the minimum of windage and a lower Centre of Gravity with the cutter rig. 

d. The mast on a cutter can be stepped nearer the point of maximum beam and is therefore more efficiently and reliably stayed. 

e. The mast can be deck stepped over the main structural bulkhead, which spreads the loads into the whole hull, this prevents leakage into the hull and gives more space and easy fore and aft movement in the accommodation. 

f. The bowsprit and non overlapping staysail allow the shrouds to be placed on the deck edge without interfering with the sheeting angles. 

g. The rig gives excellent flexibility allowing a range of sails to be set. The sails can be reefed one at a time while still m

Electrics






















To minimise voltage drop and increase reliability a 24 Volt system is suggested for engine starting, pumps, navigation and domestic lighting. 

Batteries suggested; 

150 AH 24 V. Lead Acid. For Engine starting and the Windlass. 150 AH 24 V. Ni Cads. For Domestic, Pumps and all Lighting. 40 AH 12 V. Lead Acid. Situated at high level “surge protected” for Navigation equipment radio transmitters and Emergency lighting. 

Charging to any battery set using “smart” charging system from; 

50 Amp 24V Main Engine Alternator. 50 Amp 24V Auxiliary Diesel, capable of being hand started. 6 Amp Wind Turbine Generator. 

Optional equipment. 

240/11OV diesel alternator. Deep Freeze/Fridge. Air Conditioning/Heating.

Tankage












There are two fuel tanks, capacity 2,100 litres (460 gallons) giving a cruising range of approximately 1800 miles. The three independent water tanks have a total capacity of 2,200 litres (483 gallons) and give at least 500 man days of drinking water. Their arrangement is designed to minimise free surface, to maintain fluids at the lowest CG. and to minimise changes of trim during use. 

Deck drains can be diverted into the water tanks giving a potential 800 litres per cm of rain. (450 gallons per inch) 

The rudder can also be used as an additional fuel tank, capacity 170 litres.(40 gallons)

Safety






























































This vessel is designed to sail to areas which lack any rescue cover. Self sufficiency and safety were prime considerations in the design concept, thus; 

Steel construction was chosen because of its great strength, reliability, adaptability, reparability, longevity and economy. It is the first choice of many experienced “Blue Water Sailors” 

The vessel has been computer designed, enabling the hull to be easily and quickly built ( approx 2,000 man hours ) from a flat pack kit, of shot blasted and primed, submerged plasma cut steel. These parts are accurately profiled to +- 1 mm for immediate use. The profiled shapes include locating tabs and slots. The vessel can thus be quickly and accurately built by anyone having the necessary welding skills. 

The plating is generally 1 to 2 mm thicker than would normally be expected on a vessel of this size. The main framing is close spaced for strength and transverse to allow condensation run off. It is “eggboxed” with four longitudinal deck girders and two heavy bottom girders, spaced to accommodate the engine room and water and diesel tankage. This gives a fairer hull with massive strength and longevity. This heavy duty construction makes the hull approximately 50% stronger than “normal”, while adding only 7% to the final displacement. 

The keel base is 25 mm, and the sides 10 mm. The bilge ( where a vessel would lie over when grounded ) and bottom plates are 7 mm to 150 mm above the waterline. The crew of this vessel are not playing Russian roulette with semi submerged containers, whales and tree trunks. These thicknesses also provide security in the event of an inadvertent grounding while exploring uncharted areas. 

The topsides and deck ring are 6 mm to minimise possible collision damage and to allow the vessel to safely rub shoulders with fishing fleets in port. The rest of the deck is 5 mm to support deck cargo and minimise distortion. 

The wheel-shelter is of 4mm and 3 mm plate. ( The wheel-shelter has large windows and is not necessary to the watertight integrity of the hull ) 

Five transverse WT bulkheads provide fire breaks and divide the accommodation into fully watertight compartments. The vessel will float when any single and in some circumstances two adjacent compartments are flooded. 

There are only two skin fittings below the waterline and these are fitted with standpipes. The main deck hatches are on the centerline. 

Corrosion. All plates are shot blasted and weld primed before cutting. As far as possible all parts of the vessel are easily inspectable. The frames are transverse reducing water traps. Deck and cockpit edges and other wear points are lined with stainless steel. Water traps on deck are minimised. A complete marine paint system is used with foam on the inside of the hull to eliminate condensation.

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