Please can you explain a little more about what you are asking, are you talking about the propeller?

Mike Edwards

Seal 28 "Aztec"

I will try and give you the details of my propeller.

Unfortunately the sizes will be in English inches.

My original propeller was 14 x 10, 2 blade, and was coupled with a 2:1 gearbox to a 12 horsepower Petter Mini 12 diesel engine.

I have replaced this propeller with a new Vetus 13 x 9, 3 blade propeller which is coupled with a 2:1 gearbox to a Beta (Kubota) 20 diesel engine.

The speed obtained in each case is about the same 6.5 knots maximum at about 3400 rpm, maybe slightly more with the 20 horsepower engine. But the 3 blades give a smoother drive and work better in rough seas. It also stops much faster when manouvering into a tight berth.

From your photographs it looks like you have the original Bukh 20 or 24, you should be able to go faster than 4 knots. I suppose you have checked you speed log for accuracy.

What propeller do you have?

Mike Edwards

Seal 28 "Aztec"

Neil Sinclair

Seal 28/27

'Andiamo of Exe'

Neil Sinclair

Seal 28/27

'Andiamo of Exe'

ok it with the 3000 rpm, I was not ready over.jeg will indeed be a good friend a old engine but I have tried with several rpm. but after 2400 rpm it's just as if it just whips and come nowhere my propeller is a 16x12 but the area of leaf is not large, I have put a few pictures on my website under the pictures it could be that it helped with one minor propellers with larger surface area of leaf there is plenty of surplus power is a Bukh dv20 [:)]

Lars Kruse

seal 28 primadonna

Mike Edwards

Seal 28 "Aztec"

Mike Edwards

Seal 28 "Aztec"

RH is right hand rotation, that is, clockwise as you look at the screw from aft. I think your screw is correct from your pictures. Mine also has narrow blades. Maybe your screw is cavitating? This is a problem for some Seal 850 boats. There is insufficient space between the blade tips and the bottom of the hull and between the screw and the shaft bearing. For the Seal 850, it has been solved by moving the screw a small distance (25 mm ) aft and by making a fairing to fit over the shaft bearing. Not so easy on the Seal 28! I will try and get a photo of my 2 blade screw for you.

Neil Sinclair

Seal 28/27

'Andiamo of Exe'

Lars Kruse

seal 28 primadonna

Neil

Neil Sinclair

Seal 28/27

'Andiamo of Exe'