scorpion hull stats

gtflash · 16 January 2006, 16:12

does anyone know the stats on a scorpion hull, whats its dead rise at transom, midship and bow.. will help settle a friday nite squable..

thanks gt

Mollers · 16 January 2006, 17:09

Quote:

Originally Posted by gtflash

does anyone know the stats on a scorpion hull, whats its dead rise at transom, midship and bow.. will help settle a friday nite squable..

thanks gt

Must be a right laugh, having a beer with you guys.

moresauce · 16 January 2006, 20:18

I would think that 'Searider' is the man for this sort of thing. He should be able to help you out.

moresauce · 16 January 2006, 20:19

Quote:

Originally Posted by Mollulnan

Must be a right laugh, having a beer with you guys.

Yeah, good point, favourite pub conversation on a Friday night has to be, top ten film breasts!

Searider · 16 January 2006, 20:35

Deep at the stern.

Very deep at the bow.

Deeper than most and very narrow waterline beam.

To dark and windy to go outside with my protractor and tape measure!

Pete7 · 16 January 2006, 20:43

Quote:

Originally Posted by gtflash

does anyone know the stats on a scorpion hull, whats its dead rise at transom, midship and bow.. will help settle a friday nite squable..

thanks gt

Willing to bet the deadrise at the stern is a convex curve rather than single angle.

Pete

Searider · 16 January 2006, 20:45

Quote:

Originally Posted by Pete7

Willing to bet the deadrise at the stern is a convex curve rather than single angle.

Pete

Have a green blob Pete.

Pete7 · 16 January 2006, 21:06

Oops be accused of rib spotting again

gtflash · 17 January 2006, 02:35

QUOTE=Pete7] Willing to bet the deadrise at the stern is a convex curve rather than single angle.

Pete [/QUOTE]

sorry pete you lost me there!! can you explain

and the best breasts and tightest hot pants conversations usually start once were out the dingy local and at first sign of lady flesh!

later in evening conversation revolves around best kebab in soton and garbled messages about something we can never remember

Pete7 · 17 January 2006, 08:41

Sure, I have taken a page out of the JW bible and drawn a quick diragram which might help explain. The Scorpion hull rather than having flat panels to the hull is actually a compound curve. Looking at the stern you will see that the deadrise rather than being a straight line is a gentle convex curve shape so its steeper towards the outside of the hull and shallower at the very bottom of the hull. Making the hull angle shallower at the bottom will help to produce lift particularly at the stern. I think you could describe the hull shape as "delta conic" which is interesting because although the Scorpion hull shape was drawn by a professional naval architect David Marsh in about 1995 it is very similar to the Osprey XR24 which started production 3 years previously. Even the advertising at the time which included a line drawing of the hull shape looked like an XR24 and used the same moulded deck system. Possibly just a similarity, but its sure to have Scorpion owners jumping up and down in protest

Pete

Searider · 17 January 2006, 09:25

Nice drawing!

It's a bit like that but its two curves that still meet in a point at the bottom.
Can't work out how to do drawings though.

I wonder if the vee of a Scorpion is deeper at the bow than the Viper - I don't think the Scorpion is as fast as some other 6.5m boats and this could be one of the factors.

Pete7 · 17 January 2006, 09:43

Quote:

Originally Posted by Searider

Nice drawing! It's a bit like that but its two curves that still meet in a point at the bottom. Can't work out how to do drawings though. I wonder if the vee of a Scorpion is deeper at the bow than the Viper - I don't think the Scorpion is as fast as some other 6.5m boats and this could be one of the factors.

Thanks drawing was done in MS Paint because I don't have anything else at work.
If you look directly at the nose of a Scorpion the bow has an astonishingly deep V shape and is a very fine almost knife like shape, both the Viper and XR24 are much fuller. Be interesing to measure it sometime but I would guess at 60 degrees. Whether this produces a better hull is probably subjective and would depend on what the rib was being used used for. Certainly the very fine bow ought to be good for cutting though that horrible Solent chop created by all those dreadful speed boats that clutter up our waters.

Pete

gtflash · 17 January 2006, 11:08

i suppose the constant curve and lack of flat surface increases strength too.. used to be one guy on this forum that constantly shouted that scoprs stuff easily unsubstantiated.. however with a fine bow and deep aft it must make them more ideal for head seas than following (ps i love scorpions and their ride all owners

)does the xr24 have this gentle convex too?? anyone know the actual deadrise at transom on scorpion?

Pete7 · 17 January 2006, 12:44

The Original XR24 did have a "delta conic" hull however Osprey modified it early on with a huge flat planning wedge tapering to a point about half way along the keel. They also removed the flooding hull which owners didn't want. This produced a light weight 24 foot rib capable of high speeds with a 1/2 tonne payload which remains a very competent hull today, well IMHO.

The deadrise of the Scorpion is variable so not sure how you could measure it at any one point and produce a meaningful measurement to compare it to a hull with flat panels.

Quote:

Originally Posted by gtflash

make them more ideal for head seas than following

possibly but most Scorps I see out and about are lightly loaded & have good power to weight (just a few crew) rather than say a heavily loaded dive boat so more likely to rise to / power over a following wave. They are also very expensive so owners likely know what they are doing and take care and pride in there ribs rather than the forgotten and forlorn club rescue or dive boat.

Pete

Searider · 17 January 2006, 15:04

Quote:

Originally Posted by Pete7

owners likely know what they are doing and take care and pride in there ribs
Pete

Flattery will get you everywhere.

Have only driven my 6.5m Scorpion but can confirm that the fine bow is great in a head sea.
It does tend to put its nose in the air a bit but maybe this is because you can drive quite hard up sea and are bound to catch a bigger one every once in a while.
Observing larger Scorpions they seem to do the same.

Never stuffed mine - but tend to be careful going downwind.

The only downside of the very fine bow that I have experienced is that if you are going diagonally across the sea and don't land level (athwartships) the bow can hook causing the boat to steer off to one side. Have nearly fallen out twice doing this.
Once by accident on the way to Weymouth, the first time my Brother had driven it, and once when driving "enthusiastically" over the wake of a ship to see what would happen. Think I'll slow down a bit going over ships wakes in future

Would be interesting to see what a larger one is like to drive. Must work harder and save some pennies.

jwalker · 17 January 2006, 17:56

Quote:

Originally Posted by Searider

The only downside of the very fine bow that I have experienced is that if you are going diagonally across the sea and don't land level (athwartships) the bow can hook causing the boat to steer off to one side. Have nearly fallen out twice doing this.

Yeh, that can be vicious. Searider, make sure you have no play in the steering and engine mounting(s) and/or bearings. If you have no play and it still does that....oooww.

Pete7, is it gen that the hull is a continuous curve on each side?

Hugh Jardon · 17 January 2006, 18:20

Quote:

Originally Posted by Pete7

The Original XR24 did have a "delta conic" hull however Osprey modified it early on with a huge flat planning wedge tapering to a point about half way along the keel. Pete

and here is an example of the flat planning wedge

Rogue Wave · 17 January 2006, 19:07

Quote:

Originally Posted by Searider

.

The only downside of the very fine bow that I have experienced is that if you are going diagonally across the sea and don't land level (athwartships) the bow can hook causing the boat to steer off to one side. Have nearly fallen out twice doing this.
Once by accident on the way to Weymouth, the first time my Brother had driven it, and once when driving "enthusiastically" over the wake of a ship to see what would happen. Think I'll slow down a bit going over ships wakes in future

.

firstlys your brother is a bit of a headbanger behind the wheel, he hearly went faster than me once in you Avon 5.4.

Re the hook problem it can be nasty, however there is a real cool technique which takes the problem away without speed reduction. I can't be arsed to explain it here but I'd be delighted to show you!

Pete7 · 17 January 2006, 21:34

Quote:

Originally Posted by jwalker

Pete7, is it gen that the hull is a continuous curve on each side?

JW, the curve isn't immediately obvious. with a straight edge against the transom the curve is about 2 inches out at the widest point. The bow looks almost flat so whoever made the mould must have had some fun.

Pete

gtflash · 17 January 2006, 22:00

had a look at scoprion hull today, ur right pete about the continuous arc.. but im trying to make up my mind what the advantage is, i presume a curved surface is stronger than a flat one but wouldnt increase surface area?? would that not make it less efficient and more slammy than a straight line type varying deep v