Outboard Fins (Doel Fin)

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Outboard Fins (Doel Fin)

Hi All,

I was able to take Lupus out sans mast and with a fairly flat sea and was able to stretch her legs a bit. I noticed that she needs a little help getting on the plane and staying there. I think the prop pitch is good for an Ali and will be looking at a stainless steel 4 blade next year. However I'm thinking of getting some Doel Fin outboard Fins to lift the bum a bit.

Id be interested in any views or information of people trying them. Or if you have tried a 4 blade stainless prop.

Engine engine engine 50hp

Engine engine engine 50hp Yamaha one thing after another gear position switch, tilt switch, still showing fully up when not,

Now overheat problem, warm up with revs gears not engaged 5mins and alarm screaming mechanic tried running without stat but still overheating, mechanic has ordered new stat and impeller,but I'm not convinced as because covid only 10 hours since last service when these were replaced. 1260 hours use x installed 2005

Any ideas would be appreciated.

I wouldn't say I'm any form

I wouldn't say I'm any form of experts on these, did trim stop working when overheating?

Whats the water flow rate when you connect to a hose, powerful?

Also is engine in water during the 5min to overheating or is it on water muffs? I was always told not to rev an engine when out of water.

My 2cts

Hi Ian, is this a 4 stroke or

Hi Ian, is this a 4 stroke or 2?

Again no expert, but I assume you are getting water out tell tale? If not then trace the pipe work back to the fitting on the engine (I expect mechanic would have done all this but..)

I have a 4stroke yam 50 and had reduced flow from tell tale (but no overheat). I removed the brass pipe fitting from which water exits the engine to tell tale and found a small piece of gasket material sat in there. Constricting parts where debris can collect are the brass fitting and t piece that connects in the tell tale (and also the tell tale itself).

I ran the engine briefly without the brass fitting in to blow out any other debris that was kicking around in there.


Regarding fins,  I fitted

Regarding fins, I fitted them. Not sure they have made any difference , plus may increase drag. I find best speed is with just a touch of upward angle of prop. Too much slows boat.

Regarding overheat , I had this happen straight after a service. Inspection of the internal anodes had caused one to break off and block the cooling channels. Engine had to be stripped down. Learning point, if you pull out the anode replace it.

I hope you don't have my problem but just a thought.


Also 're trim switch. The one

Also 're trim switch. The one on the throttle fails after a while. Expensive to replace so I fitted two separate buttons. Later I found trim problems intermittently. Would always go down but not up. My engineer said that the relay was failing. I finally got fed up and changed it this year...problem solved. 300.00 approx. Easy to fit.


I have had an ongoing problem

I have had an ongoing problem with the trim switch in one direction regularly using the switch on the engine, but no problem with the relay. At the beginning of this season I took the micro switch apart, cleaned, greased and back together. Quite easy if fiddly tiny springs. Has worked fine all season. The switch is a standard component.