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Boatbuilding Tips and Tricks

Wednesday, February 15, 2012

What Size Outboard for Your Homebuilt Boat?

I get questions all the time about maximum and minimum sized outboards for homebuilt boats. These things are rather hard to determine unless you know a lot about the boat, the type of water, and the boat owner's preferences. There are certain guidelines however that you can calculate to determine the maximum power based on both the US and Canadian Coast Guard recommendations.

The Coast Guard calculations are based on boat hull shape, boat length and the boatís transom width. It is explained in the US Coast Guardís publication, Safety Standards for Backyard Boat Builders. I provide a link to a pdf file of their publication on the Free E-Books, Videos and Reports page of the Spira International Web Site. In addition to horsepower recommendations, the Safety Standards also include recommended flotation, loading, identification, ventilation, and other safety recommendations for homebuilt boats. Itís a worthwhile read for anyone considering building a boat.

For those who are math challenged, Iíve run the basic calculations for my power boat designs, in a spreadsheet, and also added my recommended power for these designs. You can download a pdf of these calculations here: Boat_Horsepower_Calculation.pdf.

- Jeff

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