prop advice

[Overfinch]

High fives are very easy to spin which is a bit counter intuative, mine will spin a 21" 5 blade to the limiter 5100 rpm but a 21" x 15 3 blade to only 4500. Blade diameter makes a big difference 600-800rpm less for every inch extra in blade diameter. I suspect your drive ratio is relatively high in the Draco and it's a heavy boat assuming all is healthy you need to go down in pitch significantly 17 or even 15. Unfortunately all my props are 21" and above. Is the Draco deep V like my fletch because these hulls behave differently to the bayliner and maxum boats that I have had before which I found straight forward to prop correctly.
The deeper V digs into the water especially when loaded with people it is a slower hull than a more generic American boats but in every other way it is superior especially ride and handling. Alternatively you could always gain the 1400rpm by supercharging the 5.7 I have always been tempted by this option....

[betty boop]

managed to scrap off 8 years of init foul and found the markings on the original prop are M14 1/2 x 19P 0507B SORABO comparing that to what I had on Betty which is marked 14.25 x 21P both Ali and the SS prop is marked just 21P Lazer 2.

So now Im looking for a spare/new prop. that matched the original. Id still like a SS prop but open for offers if I can't find one.

[Ianfs]

19 pitch sounds about right except that I would say most times an SS of the same size can add one more inch to the pitch.
That 21 SS therefore may have added 2" to the pitch.

[betty boop]

19 pitch sounds about right except that I would say most times an SS of the same size can add one more inch to the pitch.
That 21 SS therefore may have added 2" to the pitch.

yes goodpoint - ive ordered a new ali prop for a bargain £60 theprice of a repair at steel developments so will see how that goes. can props be trimmed / reshaped to match and is it worth it? otherwise i'll have a 21P SS prop to hold up some shelves in the new shed.

[Ianfs]

Silly boy, you could have borrowed my spare 19p for free.

[betty boop]

Silly boy, you could have borrowed my spare 19p for free.

yes but the word there is 'borrowing' I need a keep one but thanks anyway.

the cheap one I was sold typically wasn't, I was told it would fit the merc hub kit i have but it doesn't - so now need to buy it for extra, which makes it more than the merc prop I was going to buy- to say Im Angry is an understatement


This may of use to though

http://www.mes-marine.co.uk/downloads/michigan-wheel-propellers.pdf

[shibbs]

A useful website that, thanks for sharing. Some interesting reading there.
Making me think that I need to try a 17p prop!!
Let us know how the new one runs..

[betty boop]

A useful website that, thanks for sharing. Some interesting reading there.
Making me think that I need to try a 17p prop!!
Let us know how the new one runs..

keypart.com have lots of SS props on final reductions down 1/2 price, very reasonable but Im thining they just wont fit for me & Steel Developments also have recon SS props for about £150. both worth a look if anyone is after a change,
Im thinking I'll hold back for now and see how the Ali plays out and keep an eye on flee bay for a 18p SS - too may other things I need ASAP before the end of the season - I'll probably scrub down the damaged prop just for shallow water and keep the new one for the sea just in case I prang it.

[shibbs]

I've got 2 I need to sell as they are of no use. One is wrong type for drive leg, one is too larger pitch.
Think I'd like to try a couple before buying. Even at £150 it's still too much to take a chance on. Agree with you Betty, too many other things that are needed as well!

[argonaut]

It is not hard to match a prop to a boat .... if you want to check yours is OK you just need to know the WOT range of the engine, run boat in normal load at full throttle and see if engine operates in WOT range. It will immediately tell you if pitch is right.

Stainless is always better than Ally as long as your engine has power to turn it.

Now whether you go for 3, 4, or 5 blades depends on what you are going to use boat for ............ in my case its is all about low end pull, easy planing & performance up to 26mph ....... and ability to maintain speed under changing loads - not after to end speed, so I have a pitch matched HighFive stainless prop. (will still hit 48mph though)
You may be after efficient cruising or maximum top end .... different props for different functions - but all need to be correctly pitched for your boat.

The boat came with a 4 blade Ally prop which was also over pitched. (shows dealers don't get it right), swapped it initially to a SS Revolution 4 ... it was great for high speed but no good on acceleration, so then changed to High Five. ( This prop would not suit you unless you are doing watersports)

If you are unsure of what prop you need go to Mercury prop wizard page - it will give you the correct matched prop and options.
https://www.mercurymarine.com/en-gb/eur ... #/step-one