Designers
?
Builder
Cornish Crabbers
Associations
?
# Built
?
Hull
Monohull
Keel
Centerboard
Rudder
Transom hung
Construction
GRP

Dimensions

Length Overall
24 10 / 7.6 m
Length On Deck
20 11 / 6.4 m
Waterline Length
19 11 / 6.1 m
Beam
7 10 / 2.4 m
Draft
1 10 / 0.6 m 4 5 / 1.4 m
Displacement
3,090 lb / 1,400 kg
Ballast
?
Drawing of Cornish Shrimper 21
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  • 3 / 10
  • 4 / 10
  • 5 / 10
  • 6 / 10
  • 7 / 10
  • 8 / 10
  • 9 / 10
  • 10 / 10

Rig and Sails

Type
Gaff-Sloop
Reported Sail Area
254′² / 23.6 m²
Total Sail Area
254′² / 23.6 m²
Mainsail
Sail Area
?
P
?
E
?
Air Draft
?
Foresail
Sail Area
?
I
?
J
?
Forestay Length
?

Auxilary Power

Make
Yanmar
Model
1GM10
HP
9
Fuel Type
Diesel
Fuel Capacity
10 gal / 38 l

Accomodations

Water Capacity
?
Holding Tank Capacity
?
Headroom
?
Cabins
?

Calculations

Hull Speed
7.4 kn
Classic: 5.99 kn

Hull Speed

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Formula

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

A more accurate formula devised by Dave Gerr in The Propeller Handbook replaces the Speed/Length ratio constant of 1.34 with a calculation based on the Displacement/Length ratio.

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio.311
Hull Speed = Max Speed/Length ratio x √LWL

7.44 knots
Classic formula: 5.99 knots
Sail Area/Displacement
19.2
16-20: good performance

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

Formula

SA/D = SA ÷ (D ÷ 64)2/3

  • SA: Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
  • D: Displacement in pounds.
19.17
<16: under powered
16-20: good performance
>20: high performance
Ballast/Displacement
?

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Formula

Ballast / Displacement * 100

?
<40: less stiff, less powerful
>40: stiffer, more powerful
Displacement/Length
172.8
100-200: light

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

Formula

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

  • D: Displacement of the boat in pounds.
  • LWL: Waterline length in feet
172.75
<100: ultralight
100-200: light
200-300: moderate
300-400: heavy
>400: very heavy
Comfort Ratio
14.2
<20: lightweight racing boat

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Formula

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam1.33)

  • D: Displacement of the boat in pounds
  • LWL: Waterline length in feet
  • LOA: Length overall in feet
  • Beam: Width of boat at the widest point in feet
14.15
<20: lightweight racing boat
20-30: coastal cruiser
30-40: moderate bluewater cruising boat
40-50: heavy bluewater boat
>50: extremely heavy bluewater boat
Capsize Screening
2.2
>2.0: better suited for coastal cruising

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

Formula

CSV = Beam ÷ ³√(D / 64)

  • Beam: Width of boat at the widest point in feet
  • D: Displacement of the boat in pounds
2.16
<2: better suited for ocean passages
>2: better suited for coastal cruising

Notes

The Shrimper 21 is the most modern boat in the range, designed to enhance all the magic that the Shrimper series offers with a continued focus on the classic finish and build quality yet offering more space and some new features.

The lifting keel gives a shallow 1’10” draught making her ideal for both cruising and inshore exploring. Drying moorings are easily accessible keeping running costs to a minimum.

The rig is optimised to make the boat easy to prepare for launching using a clever pivoting bowsprit making mast lifting safe and easy. The very simple track & strap mainsail attachments streamline the rigging process.

Unusually for a boat of this size the standard boat features a Yanmar 9hp inboard Diesel. This sets her apart from the other trailer sailors on the market.

The self draining cockpit is well protected with high coamings and has room for up to 6 adults. Spacious cockpit lockers to port and starboard offer dedicated battery, water and gas storage. Teak inlays are a stylish option.

Below deck the accommodation is satisfyingly generous including a well-appointed galley with a double gas burner and fully plumbed sink. A full size double forward v-berth is easily accessible from the saloon with 2 full length settee berths extending under the cockpit. A sea toilet can be fitted as an option under the forward berth.

Every boat is built to order with exterior colours and interior layout finished to your liking. Top quality deck fittings, sails and boom cover come as standard.

Hull Construction: Hand laid solid GRP hull with no foam core. Integral centerplate case laminated as part of the complete hull structure. Internal bunk and forepeak moulding bonded into hull with internal structural bulkheads bonded to both hull and deck mouldings. Standard colours are Off White, Dark Blue or Dark Green. The hull and deck joint is by way of an overlap or ‘Biscuit Tin Lid’ with GRP bonding.

Rudder: The rudder is transom hung on two stainless steel hangings bolted through the transom with Hardwood backing pads. The rudder is constructed from laminated Plywood with a stainless steel lifting drop plate. Engine Beds: Engine beds are incorporated in the GRP bunk moulding with mild steel mounts bonded into the bed design, which incorporates an oil drip tray.

Ballast: Ballast is by way of iron punchings encapsulated in resin inside the hull keel moulding. A galvanised steel centerplate forms part of the ballast with a stainless steel lifting wire leading to a winch lifting system operated from the cockpit.

Boot Top: A single boot top moulded in gel coat located above antifouling level. Colour in contrast to main hull and normally matching the deck.

Deck Construction: Hand laid GRP with Balsa core in way of horizontal load areas. Hard wood pads under deck fittings and stress points.

Cockpit: Cockpit locker lids are hand laid with Balsa core. There is integrated non-slip on horizontal surfaces with an optional two-tone colour. Cockpit drains are located aft in the main foot well with additional drainage from the seats. Watertight lockers offer storage for batteries, water & gas. A central locker houses the diesel engine when fitted.

Deck Fittings: Bespoke deck fittings including bowsprit, tabernacle and chain plates are made from stainless steel. 4 stainless steel deck cleats are positioned aft & amidships with two fairleads feeding a teak sampson post forward. All sail controls are led aft to rope clutches / jammers with a single halyard winch to starboard. Adjustable sheet cars. Access below is via a teak lined sliding companionway hatch and split plywood / Perspex washboards. Extra ventilation provided by an aluminium forward hatch.

Ports: 2 aluminium fixed ports are fitted one each in the deck topsides.

Chain plates: Chain plates are in stainless steel and through bolted on the hull sides.

Vents: Ventilation is via a washboard vent and opening forward hatch.

Miscellaneous Equipment: Fuel filler &tank vent.(Inboard version only), Life harness attachment point by the companionway. Rope tidies for halyards.

Cockpit Lockers: Two main watertight lockers with latches and padlocks are provided. A padlock is also provided for the companionway hatch.

Mainmast: Laminated in Sitka Spruce and treated with Sikkens Cetol including a stainless steel mast band to take Cap shrouds, jib and mainsail halyards. All deck mounted on a substantial stainless steel tabernacle.

Main Boom: Laminated in Sitka Spruce and treated with Sikkens Cetol including a Stainless steel gooseneck fitting, kicker and mainsheet bands and all associated reefing line leads / terminals.

Bowsprit: Laminated in Sitka Spruce and treated with Sikkens Cetol including a stainless steel pivot fitting, end plate and bobstay take off points.

Gaff: Laminated in Sitka Spruce and treated with Sikkens Cetol including a Stainless steel gaff collar with rubber protection on bearing surface. Wire hoist span and block.

Standing Rigging: Lower shrouds & forestay in 4mm 1 x 19 stainless steel wire with swagged ends. Chromed rigging screws. Jib mounted on reefing spar and controls led aft to cockpit.

Running Rigging: Main throat / peak halyards – 8mm braid. Jib & staysail halyards – 8mm braid. Main topping lift – 8mm braid. Mainsail reefing lines – 8mm braid. Mainsail outhaul – 8mm braid. Mainsheet & Jib sheets – 10mm sheet rope. All associated blocks for purchase tackles.

Mainsail: Dacron in tan or cream. 2 reef points with tie in lacing.

Jib: Dacron in tan or cream with wire luff and tell tails.

Boom Cover: In maroon, or cream acrylic. Fixings to allow for topping lift and mainsheet take off. All sails supplied with, sail numbers, logo and ties.

Engineering

Outboard Version

Outboard well: A teak engine mounting with stainless brackets. Engine well hull blank. GRP moulded fuel tank stowage and fuel lead splitter through aft locker compartment. (fuel lead not supplied as standard)

Inboard Version

Stern Gear: A 1” stainless steel shaft is fitted connected to the engine via a coupling and fitted with a Tides Marine ‘lip seal’ gland. The shaft drives a fixed 2-bladed propeller.

Engine: Yanmar 1GM10 9hp marine diesel engine. A 55 amp (12V) alternator is fitted to the engine.

Engine Instruments and Controls: The engine instruments are located at the rear of the cockpit coaming and are recessed with a clear cover. Instruments include audible alarm, alternator warning light, start switch and stop control. A single lever engine control is supplied and fitted in the cockpit well.

Engine Cooling: The engine is directly salt water cooled. A 1/2″ diameter pipe leads from the main seawater inlet through a strainer to the engine and discharges overboard through the exhaust.

Engine Exhaust: A flexible exhaust hose connects the exhaust via a swan neck with water trap to the outlet fitting through the transom.

Fuel System: A plastic diesel tank with a capacity of approximately 38 litres, breather and integrated fuel gauge. The tank is fitted with flow and return lines, the flow line having a manual shut off valve.

Plumbing

Bilge System: 1 x Manual bilge pump operated from the cockpit with a handle stored in the aft locker.

Fresh Water Tanks: 2 x 10ltr plastic jerry cans with manual hand pump. Also a bucket / sink.

Soil System: When fitted the heads discharge directly to sea via a vent loop and skin fitting.

Inlet / Outlet Fittings: Engine:** In through a single skin fitting with a valve and strainer, out via the exhaust system.

Gas System: There is a double burner hob cooker attached to a separately stored gas bottle. 12 volt DC system

Batteries: Engine – one 12 volt 88 amp/hour. (Optional on outboard version)

Charging: Via main engine – a 35 amp (at 12 volt) alternator.

Switchboard: An optional switch panel is fitted to boats that have additional electronics fitted.

Miscellaneous Standard Equipment

Deck: 1 x winch handle. 1 x bilge pump handle stowed in aft cockpit locker. 1 x fire extinguisher – situated down below.

Joinery: The interior joinery is constructed from high quality materials and in accordance with good yacht practice. Bulkheads and side back linings are from plywood.

Finish: All cabin woodwork is finished in a mix of painted bulkheads and varnished trim.

Soles: Laminate, teak and holly sole boards fitted as standard.

Upholstery: A choice of soft or wipe down plastic upholstery is available.

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