Propeller testing and reviews mercury vs solas

Discussion in 'Props' started by mcl, Sep 7, 2018.

  1. mcl
    Joined: Mar 2017
    Posts: 5
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    Location: Finland

    mcl Junior Member


    Ive done some propeller testing on my boats and thought id share what ive learned.

    The boat in question is a front cabin boat with length of 6m(20ft) and width of 2,2m. Hull is quite flat aft but has a progressive V angle and certainly not a fast hull.
    Engine is 2.5l ford diesel that i built and mated with a alpha one outdrive with 1.5 gear ratio. The exact hp for the engine is unknown,I would quess in the 120-130hp range but supossedly they can make up to 160hp with these injectors.

    The props I have tested is a solas saturn 19pitch,solas titan hr4 in 19 and 17 pitch and last a mercury vengeance 19 pitch.

    The reason for trying mainly the solas propellers was that they are cheap(~300usd) compared to mercury propellers that starts at 500.

    The first prop was the saturn,quite fast to plane but would not allow any trimming before the boat started porpoising,top speed 31 knots at rpm unknown because tach was not functioning back then.
    The saturn is in my eyes a solas copy of the merc vengeance.

    The titan hr4 19 pitch would barely get the boat on plane,way to heavy.The titan hr4 propellers are thick.The propeller has alot of rake and cup and is heavy to spin.I would barely get on plane with just me in the boat.To much pitch combined with not building boost at low rpm.Top speed was 27 knots and 2900rpm

    The 17 pitch hr4 was alot better,the boat would still plane quite easily with 3 people onboard, I would quess 5 people would be the limit where it would really struggle.This prop also suffers from the boost problem,with so much surface area the prop wont slip getting the engine to rev up to where it starts building boost. The prop gives alot of stern lift,you can trim it quite a bit although it would still quite easily porpoise. I usually march at 22 knots and and top speed of 29 knots with 3300rpm.

    The last prop i tested was a mercury vengeance.This is very common prop and thats why you can get it almost at the same price as the solas props.It doesnt have alot of rake and cup,blades are quite thin which will easily cut through water.Other mercury propellers you usually have to pay alot more. Usually you get what you pay for and this is the case with solas vs mercury. The finish is just alot better with the merc props,the solas propellers are really unfinished with square shaped leading edges(some parts 1mm wide not really hydrodynamic),the blades are alot thicker which increases drag. I have a balance stand that i balance motorcycle wheels on and the 17 pitch solas the static balance was way off. Solas claims the balance their props dynamicly so cant really comment more on this.I also used a dial indicator and the hub was out of round by 0,5mm at worst.
    Getting to the vengeance this prop will spin alot easier getting the engine to boost and make power,it slips quite a bit during planing so planing time comparable to the 17 hr4 even though it gets to the meatier part of the powerband powerband faster. I can march at 25 knots and 3000rpm and if i floor it will go straight to 4000(rev limiter).I havent tried the top speed since i dont rather enjoy revving a diesel to the moon,but it will obviously be the best of the group. You can really feel how much more easily the vengeance pushes the boat,need far less throttle for same speed so your putting less strain on the engine. I could go up in pitch with this prop for speed but the idle is already really high with this gear ratio on 800rpm idle.

    To sum it all up:
    -You get what you pay for,there is a substantial quality difference between merc and solas propellers. The solas looks like it has been pulled out of a cast and polished.
    -I only balance tested and measured the one solas prop but found people with similar issues on youtube so i dont think its a one time ocurrence
    -If you have a low hp application thats is mainly used at 25 knots,maybe dont buy super performance propeller with thick blades,alot of cup and rake.Your wasting hp spinning a heavy prop to get certain qualities(bow lift that you dont necessarily need in a low speed vessel).
    -A performance propeller with alot of rake and cup means the prop can run closer to the surface without ventilating or blowing out,with a outboard thats means you can lift the engine up higher and get less drag and thus more speed.If you have a sterndrive which is fixed height and usually quite deep in the water from the factory then all these benefits gets unused.
    -I did like some handling properties on the titan hr4. But the vengeance is just heaps better and puts less strain on my drivetrain, I would still maybe like to try out a enertia or similar propeller.
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