Scandinavian lapstrake,Flatsawn?

[yorgie]

Most wooden boatbuilders swear that all planking should be edgegrain.But most photos of scandinavian boats show flatsawn planks. The norwegian boatbuilders who led the the construction of MUNIN,a 40' Gokstad replica, insisted on flatsawn,saying that edgegrain will split at the laps.We've had to replace several planks in the four years since MUNIN was launched but most of these planks were damaged by the trailer or had some twist in the grain.

Flatsawn planks are easier to obtain for the
large planks needed on traditional nordic boats.Does anyone know how well flatsawn planking holds up in these boats.

[lagspiller]

I am not sure what is meant by flatsawn/edgegrain, but here our sail club has a small fleet (about 20) of boats built in the same construction tradition as MUNIN. The oldest is 90 and still going strong - newest just launched this year. Same building method, same materials. Boardwidths around 60 cm.

[ 10-16-2004, 09:23 AM: Message edited by: lagspiller ]

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/3075040/40075424.jpg

http://pic3.picturetrail.com/VOL12/1104763/3075040/40075419.jpg

http://pic3.picturetrail.com/VOL12/1104763/3075040/40075413.jpg

Takes a big log to mill rift or quartersawn (also called "edge grain" or "vertical grain") boards of any width. Some cold places....parts of Alaska come to mind...don't have any big trees.

Flatsawn (also "plain sawn" or "through-and-through") wood has the advantage of taking fasteners with less risk of splitting at the disadvantage of almost twice as much seasonal movement. Allow for that movement by using traditional construction with stable species like cedar or spruce, no fabric/goo and not allowing the boat to dry out too badly and it isn't a problem...

...but move a carvel troller hull of flatsawn Doug Fir, which moves some...a hull that's been immersed in cold Puget Sound water 50 weeks a year for 30 years to Arizona for rebuilding, and you are inviting disaster.

[ 10-16-2004, 10:56 AM: Message edited by: Bob Smalser ]

[yorgie]

Thanks for posting the diagrams Bob.You're the only builder besides my norske friends to claim that there is at least one advantage to using flatsawn planking.We used free 'scrap' fir slabs from my workplace and most of the planks have held up fairly well.We couldn't have afforded 1000 ft of 1"by14" if they were edgegrain.

There was splitting in any planks that had moderate grain twist.Our other big problem is the drying resulting from an open boat being exposed to the sun for several months.A decked boat(folkboat,kosterbot) would receive much more protection.On the westcoast we don't have huge temperature or humidity fluctuations that would cause excessive plank movement.I suppose western Norway has similar climatic conditions.

Lagspiller,are you're boats the Oselver type with three huge strakes?I can't imagine trying to bend 60cm wide fir planks.We are planning on building a faering this winter but will probably use four or five strakes.Kris and Arne are from Romsdal(I believe)and I think they build with more strakes up there.