Do Trimarans Plane?
Ever wonder if a trimaran can plane on the surface of the water or not? Naval architect Michael Waters answered this technical question recently at the SmallTrimaranDesign.com site, which is beginning to feature some of his articles.
He offered a good explanation about what is actually happening when “planing” occurs and some of the factors involved. Among them are:
– The driving force to create a planing situation
– The type of edge on a foil that encourages planing to occur
– A formula for lift as it relates to the issue
– The factors needed for a trimaran to plane
– How ama transoms may affect whether or not planing situation might occur on a trimaran
To read more about the planing issue as it relates to trimarans click here.
August 27th, 2009 at 4:57 pm
Do trimarans or any other slender hull, such as a cat or even a kayak, plane ?
My gathered notion of planing speed is when hull displacement speed is exceeded (semi planing) or thoroughly exceeded.
I.e., if I have a 16 ft lwl hull, I would expect it to go at a maximum of 1.34 * square root of 16, which gives a figure of 5.36 knots ( 1.34 *4).
Now, if I’m clocking 6 knots it’s about normal on a slender hull, but if I’m doing 8 or 9, or more, this is way beyond the displacement speed limit. The hull is on a plane, the aft wave produced in displacement mode, is far aft of the stern, and the drag is greatly reduced.
This can happen at wind bursts, and the hull will go from semi-planing mode into planing one (read stepless plane hulls by Julian or Frank Betwaithe, designer of 49er) and backwards, but if the wind is strong and constant enough, the plane will be endless, If you have a sheltered bay and no waves you can really enjoy it :-)
This happens even in human propelled boats in appropriate conditions (surf skis and sea kayaks) , when wind and waves, even small ones, are pushing the boat beyond displacement speeds. Trim is of the utmost importance here.