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The R415 is a replacement design for the R400. The difference in overall length is accounted for by the size of the boarding platform and transom angle. The accommodation volume and the various layouts are basically the same as the R400 and preliminary enquiries are for the centre cockpit and pilot house layouts. The R415 will be be available as a full steel kit.
For a given waterline relative to the design water line, the R415 has more displacement than the R400 and when fully loaded should only be 30-50mm down on its design waterline. The R415 has even less overhang forward and a noticably longer waterline than the R400. The "bulb" keel, as drawn at 1.75, has nearly all the lead ballast in the bulb section of the foil giving a very low centre of gravity for this ballast - see stability estimates below.
Detailed study plans are not yet available for the R415, but information from the R400 could be used in pricing of this design. The R415 design work should start within a few months.
| L.O.A. | 12.65m | 41'6" |
|---|---|---|
| L.W.L. | 12.125m | 39'9" |
| Beam | 3.5m | 1'6" |
| Draft | 1.75m | 5'9" |
| Dspl | 13,000kg | 28,660lb |
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The R415 has good volume and the carrying capacity required for a cruising yacht. The following information shows the range of loading and changes in waterlines.
| Waterline | Displacement | Loading | ||
|---|---|---|---|---|
| 50mm (1") Up | 11,875kg | 26,180lb | 650kg | 1,433lb |
| 25mm (1") Up | 12,525kg | 27,613lb | 1,300kg | 2,866lb |
| @ D.W.L. | 13,176kg | 29,048lb | 1,951kg | 4,301lb |
| 25mm (1") Down | 13,840kg | 30,512lb | 2,615kg | 5,765lb |
| 50mm (2") Down | 14,516kg | 32,002lb | 3,291kg | 7,255lb |
An effort should be made to build and load the yacht within the figures recommended. Overbuilding or adding any unnecessary weight during construction and fitout will detract from optimum loadings.
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All the lead ballast is in the bulb section of the foil giving a very low centre of gravity.
The overall aim of this design is a high range of positive stability. Using the screening value formula in the Code of Practice from the Department of Transport in the UK - "Safety of Small Commercial Sailing Vessels", which estimates the range of positive stability based on various parameters of the hull (i.e. beam, displacement volume, canoe body draft, ballast ratio etc), the R415 has an estimated range of positive stability of 144+ deg. This should be achievable in centre cockpit versions of the yacht and will be exceeded by the pilot house version. See stability curves for the R14m aluminium cruising yacht for the effect a pilot house can have on the point of vanishing stability.
The table below shows the range of stability required by the Code of Practice for yachts between 9m and 23m LOA. It clearly indicates that the smaller the yacht, the larger the range of stability needs to be. A yacht at 41'6" (12.65m), such as the R415, needs a range of positive stability of 131 deg for unrestricted offshore use (Category 0) under the Code of Practice.
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