Lifting Strakes......they vary

[Tommy]

I wanted to respond to Mean Mike's question about the lifting strakes on Mikey's boat, but I didn't want to hi-jack the "Boat Lift Question" thread. I pulled my literature and found in the Sports Illustrated article in April, 1960, that a hull rendering shows only the outboard strakes carried to the transom, and the other 3 pairs got progressively shorter as the went inboard, with the strake closest to the centerline only half the length of the hull. In a 1961 ad it shows where 3 of the 4 strakes per side continued all the way to the transom, but the 3rd strake from outboard that lined up with the shaft opening died just forward of the opening. Then I found a 1963 article showing a 31 in the sling with the 2 outboard strakes carried all the way to the transom, but the 2 inboard strakes terminated just forward of the shaft opening. On the half-model that Bertram provided during the marketing of their Silver Anniversary Bertram 31 in 1986, only the outboard lifting strake runs all the way to the transom, and then the strakes are progressively shorter the further inboard that they are positioned. This is consistent with the strake layout on Island Girl which was a 1973 model. I believe a quote was attributed to Lee Dana (chief engineer for Bertram in the 60s) in the book, Legend of Bertram, that they were "constantly changing the lifting strakes in the early years" trying to find the perfect design. So I'm guessing that a lot of variation exists with regards to the location and length of the lifting strakes.

[Marlin]

When I redid my 71, I accidentally drilled into a lifting strake, the water drained for days out of the wound, and it was filled with foam, when I looked inside the bilge and approximated the strake location, I finally figured out that they were add ons, after the hull was laidup ,it now makes sense that they could play with the dynamics to help improve the performance

[Kevin]

So which design is the best?

[mike ohlstein]

So which design is the best?

The first one probably worked best. The last one probably cost the least to manufacture.........

[JP Dalik]

The early to late 70's boats are lighter on glass ( but not as light as the 80's) then the 60's hulls and have the most modern chine layout. As far as chine layout goes they all seem to run fine, I'd be curious to know if the change was for efficiency or as a result of engine technology and horsepower availability as time marched on.

The modern adaptation is considered the best handling by the folks that have worked on them up here.

Of course we all know the easiest way to tell is to count how many Chines touch the spray rail old hulls have three at the bow new hulls do not.