Surprise Twin keel

Sailboat specifications

The Surprise is a 25’1” (7.65m) one design sailboat designed by Joubert Nivelt Design (France). She is built since 1977 by Archambault (France) and BG Race (France). The Twin keel version allows a shallower draft while maintaining performance thanks to the asymmetric fins with bulb. As a bonus beaching becomes easy and stable.

The Surprise is as well listed, on Boat-Specs.com, in Fin keel and Swing keel version (see all the versions compared).

Surprise's main features

Model: Surprise
Version: Twin keel
Hull type: Monohull
Category: One design sailboat
Sailboat builder: Archambault
&
BG Race
Sailboat designer: Joubert Nivelt Design
Country: France
Construction: GRP (glass reinforced polyester):
- Hull: Single skin fiberglass polyester
- Deck: Sandwich balsa fiberglass polyester
Number of hulls built: About 1600
First built hull: 1977
Last built hull: Still in production
Appendages: Twin keel : fin without bulb
Helm: Single tiller
Rudder: Single spade rudder
Unsinkable: No
Trailerable: Yes
EC design category iThe CE design category indicates the ability to cope with certain weather conditions (the sailboat is designed for these conditions) A: Wind < force 9, Waves < 10m B: Wind < force 8, Waves < 8m C: Wind < force 6, Waves < 4m D: Wind < force 4, Waves < 0,5m: C
Former French navigation category: 3
Standard public price ex. VAT (indicative only): About
32 700 €
(2017)

Surprise's main dimensions

Hull length: 25’ 1”7.65 m
Waterline length: 21’ 8”6.6 m
Beam (width): 8’ 1”2.48 m
Draft: 3’ 4”1 m
Mast height from D_WL: 32’ 2”9.8 m
Light displacement (M_LC): 2976 lb1350 kg
Ballast weight: 1323 lb600 kg
Ballast type: Cast iron
French customs tonnage: 3.49 Tx

Surprise's rig and sails

Upwind sail area: 328 ft²30.5 m²
Downwind sail area: 662 ft²61.5 m²
Mainsail area: 178 ft²16.5 m²
Genoa area: 151 ft²14 m²
Jib area: 108 ft²10 m²
Symmetric spinnaker area: 484 ft²45 m²
I iFore triangle height (from mast foot to fore stay top attachment): 26’ 5”8.05 m
J iFore triangle base (from mast foot to bottom of forestay): 6’1.83 m
P iMainsail hoist measurement (from tack to head): 29’ 6”9 m
E iMainsail foot measurement (from tack to clew): 10’ 10”3.3 m
Rigging type: Sloop Marconi 7/8
Mast configuration: Deck stepped mast
Rotating spars: No
Number of levels of spreaders: 1
Spreaders angle: Swept-back
Spars construction: Aluminum spars
Standing rigging: 1x19 strand wire continuous

Surprise's performances

IOR rating iIOR, or International Offshore Rule, was a measurement rule system used internationally for ocean racing. It allows boats of different sizes and designs to race each other fairly. Therefore, by comparing these values, we can have an indication of the relative speed of 2 boats.: 23.6
HN (French rating) iHN or "Handicap Nationale" is an empirical rating system used in France allowing various monohulls, of different sizes and designs, to race each other fairly. It is particularly suitable for cruiser and cruiser-racer. Therefore, by comparing these values, we can have an indication of the relative speed of 2 boats.: 19.5
Upwind sail area to displacement iThe ratio sail area to displacement is obtained by dividing the sail area by the boat's displaced volume to the power two-thirds. The ratio sail area to displacement can be used to compare the relative sail plan of different sailboats no matter what their size. Upwind: under 18 the ratio indicates a cruise oriented sailboat with limited performances especially in light wind, while over 25 it indicates a fast sailboat.: 269 ft²/T24.97 m²/T
Downwind sail area to displacement iThe ratio sail area to displacement is obtained by dividing the sail area by the boat's displaced volume to the power two-thirds. The ratio sail area to displacement can be used to compare the relative sail plan of different sailboats no matter what their size.: 542 ft²/T50.35 m²/T
Displacement-length ratio (DLR) iThe Displacement Length Ratio (DLR) is a figure that points out the boat's weight compared to its waterline length. The DLR is obtained by dividing the boat's displacement in tons by the cube of one one-hundredth of the waterline length (in feet). The DLR can be used to compare the relative mass of different sailboats no matter what their length: a DLR less than 180 is indicative of a really light sailboat (race boat made for planning), while a DLR greater than 300 is indicative of a heavy cruising sailboat.: 133
Ballast ratio iThe Ballast ratio is an indicator of stability; it is obtained by dividing the boat's displacement by the mass of the ballast. Since the stability depends also of the hull shapes and the position of the center of gravity, only the boats with similar ballast arrangements and hull shapes should be compared. The higher the ballast ratio is, the greater is the stability.: 44 %
Critical hull speed iAs a ship moves in the water, it creates standing waves that oppose its movement. This effect increases dramatically the resistance when the boat reaches a speed-length ratio (speed-length ratio is the ratio between the speed in knots and the square root of the waterline length in feet) of about 1.2 (corresponding to a Froude Number of 0.35) . This very sharp rise in resistance, between speed-length ratio of 1.2 to 1.5, is insurmountable for heavy sailboats and so becomes an apparent barrier. This leads to the concept of "hull speed". The hull speed is obtained by multiplying the square root of the waterline length (in feet) by 1.34.: 6.24 knots