Pierce me baby !!!

I

itsonlymoney

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Have read a few reports on surface piercing drives of late, can't quite work it out. Can someone explain the set up, the differences between them and normal drives and the supposed benefits.

Regards - Ian

<hr width=100% size=1>Play the best game you can with the cards you've been dealt ! ! !
 
I had mine block paved, a bit expensive but if done properly will last for years. I have never heard of a pierced one, perhaps that helps with drainage /forums/images/icons/laugh.gif

<hr width=100% size=1><font color=purple> "You only see what you recognise, and you only recognise what you know" <font color=purple>
 
Very funny !!!
Your no help at all.

<hr width=100% size=1>Play the best game you can with the cards you've been dealt ! ! !
 
/forums/images/icons/laugh.gif Have a nice day! /forums/images/icons/laugh.gif

<hr width=100% size=1><font color=purple> "You only see what you recognise, and you only recognise what you know" <font color=purple>
 
Simply, prop is not totally underwater, only bottom half is.

It's usually extended out of transom, into the area where water is calm and undisturbed, so more efficient.

No legs and things to introduce drag, so more efficient.

With a traditional prop,maximum feasible propeller diameter is considerably smaller than the optimal size. This because of blade tip clearance from the hull, maximum vessel draft, shaft angle, and engine location. With a surface piercing prop, these elements removed, so can use a much bigger, more lightly loaded, and hence more efficient prop

<hr width=100% size=1>There is no such thing as "fun for the whole family."
 
Try <A target="_blank" HREF=http://www.arneson-industries.com/>here </A> for all you need to know about surface drives

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<A target="_blank" HREF=http://www.howardarneson.com>here's some stuff from the nutter who perfected them</A>, Mr. Arneson.

<hr width=100% size=1>Why'd he call me shortie?
Because you're small,...small,...S, M, all.
 
Thanks for the info guys
Brendans right cos I was reading MBY the other day and there were at least three reports on super yachts in the 1 Million + bracket that had these things fitted. Incidentally talking of MBY and the boats refered to within it, I was reading the spec on a beautifull big Yacht thing whose make I can't remember, anyway this thing did 250 GPH at something like 20 Knots 1800rpm. Can you imagine ?

No filling from jerry cans then ?

Ian


<hr width=100% size=1>Play the best game you can with the cards you've been dealt ! ! !
 
Do you know i would have never considered them for anything other than out and out performance purposes, I failed to see the benefits they afforded in normal use.


I would have thought for normal use the surface drives, offering less bow lift than standard drives, would make climbing onto plane harder especially on heavier craft and thus need larger engines plus making it harder to raise the bow as conditions dictate, even allowing that more and more surface drives are trimmable. I could possibly see them being useful on discplacement craft.

kevin
 
According to some boat tests I have read recently Neither does anyone else.

Ian


<hr width=100% size=1>Play the best game you can with the cards you've been dealt ! ! !
 
Absolutely right - it is the thrust of the forward hull that lifts the bow and boats need trimming in (ie to bring the bow down) to "hop" up onto the plane by adding lift at the stern. Then as one goes faster the centre of lift moves aft and less of the hull is in the water. Anyroad, reports on Arnesons etc imply one is more concerned to get somecavitation/prop slip to get the revs up than worry about the hull trim angle.
There have been loads of posts here about surface drives + pros + cons if the initial poster wants to know more.

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you know so much but after reading all these posts I am still more confused than when I started

be lucky

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adding weight to the stern to raise the bow is a way to get a stubborn boat on to plane, maybe not on all craft i was generalising, it drives the boat out and up.

if you keep the bow down on underpower boats it can possibly make it difficult for the craft to gain enough forward speed to get onto the plane. I think getting the bow up and out can mean less drag through the water aiding the speed required to plane, it can on some hulls also mean that as the hull surface area increases and the v decreases slightly from the bow it aids the lift up onto plane. once the bow is lifting and speed increases trim can be altered to begin to level the boat out and assist in raising the stern.

kevin
 
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