Through-hub props

[Bob T.]

Does the flare at the rear of some through hub props increase stern lift? Is it significant? Thanks B.

[Yamaha 225]

Hi there!

I can tell you about my experiences.

I had a Hurricane 470 with Yamaha 90 a couple of years ago, and ran it with Yamaha High Perf. 20" ("semi-cleaver"). I god a sharp accelleration, but not enough bow lift because the boat hadn't any setback and was to frontheavy. I put on a Laser II 20" with through-hub and good rake as well. What I saw was a tremendous increase of bow-lift! And I think this was because of the enlarged torpedo on the lower-unit. Just the same is noticed with my new boat, a Gilbert 22 and also a Hydrolift F-20.

The interessting is why? (all these boat require a bit positive trim) Is it the down-force on the highest point on the hub (which press the boat down in the stern), or is it the vacuum on the lower point on the hub (which sucks the rearest part of the prop down like a wrench and therefor raise the bow)? Interessting!

The Hurricane ran 53 miles on top with no cavitation. Both the Gilbert and Hydrolift runs 70-80 miles with over-hub props, but with Laser IIs they cavitate when 60 miles is reached----

I don't think you will see much increase in sternlift.

Prop-experts are wanted to add some more information!!


Erik Eriksen -non expert yet-