Mariner, Michigan Ballistic S'S prop Results.

[dave3235]

Hi all

For those of you that have been waiting for these results I can now say there in.

Took it out from Teignmouth on Sunday and the weather was ok in the morning and ideal as the day went on.

So the boat was loaded as this ,myself and a friend weighing in at around 30 stone,plus a bit of kit which is not really of significance.

Started with the stock aluminium 10 1/8 13p,At WOT 24 MPH was reached and RPM reached was 5,315 so was happy it was in the WOT limit of 5,500 RPM.

Changed to my new SS Michigan Ballistic prop same diameter and pitch as stock.Opening her up you could tell it was better hole shot,mid range was impresive.Opening her up to WOT which reached 23.8 MPH and the WOT reading on the tach was 5,680 RPM.

Would it be possible to get any more from this prop by sending to the prop shop as I do need to loose some revs and gain some speed, your input is all welcome Thanks

[dave3235]

Hi

Just thought I would add.
Is this the characteristics of the design.

Do you think a 15p would be a good choice going on the data.


Also thanks to admin.

[freespirit3]

I have just had some great results from a Michigan Ballistic prop on my Redbay, was about to give up on propellers but have now found the one.

Going to post a separate post on it so I don't hijack yours, as we all know we have to treat props on a case by case basis, personally I have had props re pitched and had limited success.

You would be better getting the next size available and selling your current prop.

I have ended up with a size that I thought would not work but did

STD prop 14 x 21 Aluminium (weak performance max speed 35knots WOT 5600 rpm.

S/S Ballistic prop 13 1/8 x 21 (great grip, more trim available with no loss of grip, max speed 38 knots WOT 6000rpm.
And a huge reduction in prop cavitation.

[dave3235]

Hi

I was thinking of maybe a 15p as the revs raised almost 400 rpm and this hopefully would bring my revs back to around 5,300 as before with the stock prop may be worth giving steel developments a call and see what they could advice.Also you gained revs due to the Ballistic being less diameter.
Thanks for sharing your findings.

[freespirit3]

Its all about the cup size

My understanding is that with these props they have a reduced O/D to the std equivalent with a similar pitch because the cupping of the prop blades gives a much wider surface area and hence moves a similar amount of water but with more grip.

I would check with your supplier and check out the options available to you, might see you at teignmouth one of the days, we blast down there some weekends in the summer for some fun and skiing.

[Roflhat]

think steel developments can only adjust pitch 1" either way. Probably worth giving them a call though

[freespirit3]

In my experience any of the prop companies can only tweak the edge of the blade as opposed to the whole length of the blade.

I didn't get much from a re tweak and paid £60, this was two years ago, I would have been better putting it towards another prop, which is what I have done now

[Roflhat]

They can't change the pitch at the hub but they should be able to change it over most of the blade. You could get it cupped as well, will give you more grip and effectively acts as more pitch

[dave3235]

Hi Roflhat

I will give them a call today,the prop is already cupped but could they give the prop extra cupping.Also wondering if I could px it for a 15p Ballistic or just sell it.

[dave3235]

Hi all

Phoned. Steel Developments going to a 14p would change the revs by 250 to 300 RPM exta cupping roughly changes the revs by around 500 RPM,unsure whether to have both done or just go for a repitch what's your thoughts.Also do these props like having the engine raised out of the water like a cleaver prop.

[Roflhat]

try raising the prop up a bit like it is, I'd guess it'll handle it alright due to the almost semi-cleaver design. If it's slipping a wee bit then cupping will help. Raising the engine will give you more RPM but less grip, which is where cupping usually helps.

[dave3235]

Hi roflhat

If I get the repitch and extra cupping that could in theory loose me 300 to 350 RPM, which has at max bring my revs down from 5,680 to 5,330 how many revs would I be likely to gain from raising.the engine.Or would it be wiser to sell and get a 15p.

[Roflhat]

Try raising it up the way it is and see what affect that has, very difficult to predict how it will go

[dave3235]

Hi Roflhat

I think a bit more testing is needed.Also as you mentioned raising the engine.