Reply
 
Thread Tools Search this Thread
 
Old 04 January 2005, 10:41   #1
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
hull and speed

Everybody is always talking about fast hulls and slow hulls.
But when i'm on plane and trimmed out(WOT) there is only 1 meter(or less) hull left in the water.
So if you have two hulls with the same weight, length and weight distribution(and engine offcourse), how important can the shape of the hull be???
I'm very curious.
Can anyone tell me?
Greetings Niels.
__________________

__________________
niels is offline   Reply With Quote
Old 04 January 2005, 12:11   #2
Seb
Member
 
Country: UK - Wales
Make: Humber
Length: 5m +
Engine: E-tec 50
Join Date: Jul 2003
Posts: 237
The hull shape and thus hydrodynamics are VERY important in determining the top speed of a RIB.

Think about it; if you had two cars with the same engine and weight in them but one was a sleek sports model and one was a bloated 4x4, which would be faster?

Same type of idea. The design which is likely to cut its way through the opposing matter the best, be it air or water, will be the fastest.

Cheers

SEB
__________________

__________________
Seb is offline   Reply With Quote
Old 04 January 2005, 12:55   #3
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
ok

But the hull nearly doesn't touch the water in both cases at wot.
the last meter in the water has almost the same hullshape.(both deep v)
Is it maybe only the wind resistance then?
__________________
niels is offline   Reply With Quote
Old 04 January 2005, 12:59   #4
Member
 
Country: UK - England
Town: Midlands
Make: Nautique
Length: 6m +
Engine: PCM 5.7l
Join Date: Oct 2003
Posts: 1,082
A 'slow' hull most likely won't lift out of the water in the same way as your revenger does

It might be on the plane but still have more hull in the water than a different hull shape.
__________________
simmons0 is offline   Reply With Quote
Old 04 January 2005, 13:09   #5
Member
 
Country: UK - England
Town: Nr Faversham, Kent
Boat name: C Rider
Make: Avon
Length: 5m +
Engine: Yam 80
Join Date: Jan 2005
Posts: 486
Another very important factor is how deep the Vee. In flat calm water a deep Vee hull will sit lower in the water for the same weight/speed than a shallow Vee. Hense if its lower theres more wetted surface which causes drag. So the shallow vee will be faster.
This is all fine until the water is not smooth, then the shallow vee will bounce around so hard it will have to slow to maintain control, Whereas the deep vee will be better able to cut through the wave.
Some top race boats have very deep vee's forward and rapidly flatten out at the stern to try and get the best of both worlds. I believe this is called dead rise??

As an example we paced an avon SR4 with 30hp and a SR5.45 with a 90hp. The SR4 won closely followed by the SR5.45. but when the wind blew up the SR5.45 just kept going whereas the other couldn't maintain control and had to back off.

In the overall equation fast hulls are rarely good in rough water. Its all a compromise between speed, stability and how well it will ride out a chop.
__________________
Swifty is offline   Reply With Quote
Old 04 January 2005, 13:34   #6
Member
 
Country: UK - England
Town: Bradford on Avon
Boat name: tbc
Make: Sunseeker (AshleyD)
Length: 8m +
Engine: 2 x coal burners
Join Date: May 2004
Posts: 461
Quote:
Originally Posted by niels
But the hull nearly doesn't touch the water in both cases at wot.
Yeah, know what you mean.....
Attached Thumbnails
Click image for larger version

Name:	ribsters revenger.jpg
Views:	208
Size:	65.1 KB
ID:	9900  
__________________
I miss the sound of an Etec in the morning
Brambles is offline   Reply With Quote
Old 04 January 2005, 13:34   #7
Member
 
Country: Ireland
Town: Dublin
Boat name: wizzard
Make: REDBAY
Length: 7m +
Engine: 225 optimax
Join Date: Sep 2002
Posts: 835
Hysucat
__________________
www.dublinsislands.com

WHEN THE CAT IS AWAY THE MICE GO TO REDBAY..............
gavin is offline   Reply With Quote
Old 04 January 2005, 17:58   #8
Member
 
Country: UK - England
Town: scotland
Boat name: Leviathan
Make: Phantom
Length: 8m +
Engine: GM Diesels
Join Date: Jan 2003
Posts: 1,437
Quote:
Originally Posted by Swifty
Some top race boats have very deep vee's forward and rapidly flatten out at the stern to try and get the best of both worlds. I believe this is called dead rise??
It's actualy quite rare for this hull form in out and out racing.

The term 'Deadrise' when used as a generalisation, is refering to the depth of the 'V', usualy quoted 'at the transom'.

'Constant deadrise' refers to a hull with a deadrise that is substantialy the same at the transom as it is in the forward section. (by far the most common form for all out racing)

A 'Warped Deadrise' refers to form you described with a deeper 'V' in the forward sections, than at the transom. This form gives a very soft and 'pitch stable' ride.
__________________
Jonny Fuller is offline   Reply With Quote
Old 05 January 2005, 04:37   #9
Member
 
Country: UK - England
Town: Nr Faversham, Kent
Boat name: C Rider
Make: Avon
Length: 5m +
Engine: Yam 80
Join Date: Jan 2005
Posts: 486
Jonny, many thanks for clarifying that.

That picture from brambles, if you look at the guy in the white t shirt, what was he trying to say?
Should we start a new thread "caption competition"

OK so landing gear hasn't come down.... brace brace brace
or
I told you there was a rattle from the dash when it does this.
__________________
Swifty is offline   Reply With Quote
Old 05 January 2005, 05:48   #10
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
thanks for your replies

greetings
niels
Attached Thumbnails
Click image for larger version

Name:	23holland1.jpg
Views:	226
Size:	17.3 KB
ID:	9909  
__________________
niels is offline   Reply With Quote
Old 05 January 2005, 08:17   #11
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,370
It surprises me how these ribs get there bows so high out of the water when there are almost no waves. In niels pic it looks as though the wave height is little more than about 300mm. Do your boats really handle that badly or are you just playing?
__________________
JW.
jwalker is offline   Reply With Quote
Old 05 January 2005, 09:26   #12
Member
 
Country: UK - Scotland
Town: Ardnamurchan
Make: Domar Corsair
Length: 4m +
Engine: Mercury 20HP
MMSI: What?
Join Date: Aug 2004
Posts: 215
Erk, how can you see where you are heading like that?! Do you have a camera on the bow or something?

Look's like someone needs to play with the trim!!
__________________
Mr-d is offline   Reply With Quote
Old 05 January 2005, 10:10   #13
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
just playing

we are just playing off course
only hitting the trottle a little firmly.
the bow goes as high as I want her to go.
the boat handels like a dream. 65 knots no problem.
I love this monster.
again greetings from a wet and grey holland.
can't wait till summer. and I don't think I do.
Attached Thumbnails
Click image for larger version

Name:	weekend Texel 0071.jpg
Views:	170
Size:	7.7 KB
ID:	9911   Click image for larger version

Name:	weekend Texel 0151.jpg
Views:	156
Size:	8.3 KB
ID:	9912   Click image for larger version

Name:	weekend Texel 0161.jpg
Views:	161
Size:	8.1 KB
ID:	9913  
__________________
niels is offline   Reply With Quote
Old 05 January 2005, 10:19   #14
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
and one more

on our way to ribex 2004.
Attached Thumbnails
Click image for larger version

Name:	M4100031.jpg
Views:	144
Size:	10.7 KB
ID:	9914  
__________________
niels is offline   Reply With Quote
Old 05 January 2005, 11:38   #15
Member
 
Country: UK - Scotland
Town: Ardnamurchan
Make: Domar Corsair
Length: 4m +
Engine: Mercury 20HP
MMSI: What?
Join Date: Aug 2004
Posts: 215
Hey Niels, whereabouts is hoorn? I've heard of it but i cant combine it with water somehow... braindead i guess... is it in Friesland? or where?

I wish you good luck in the summer with all the Germans in their big fat Motorboats! One way to make them scared is probably the manouvre of fast acceleration as the pics show! Ahhh, i can just imagine it "Verdammte Ar****ch! " hehe
__________________
Mr-d is offline   Reply With Quote
Old 05 January 2005, 12:41   #16
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
here it is

Attached Thumbnails
Click image for larger version

Name:	hoorn.jpg
Views:	158
Size:	25.7 KB
ID:	9918  
__________________
niels is offline   Reply With Quote
Old 05 January 2005, 15:47   #17
Member
 
Country: UK - England
Town: mansfield
Length: no boat
Join Date: Oct 2004
Posts: 405
Send a message via MSN to osprey__viper
Hoorn.......

......... is one of the nicest places I have visited in Holland . Went there on me dads boat (moonraker 36) in 1990. Two great weeks cruising the iselmere (?) with a north sea crossing at each end.

Only a couple of meters deep and some of the biggest waves you can ever wish to meet!!!!!!!!!!!!!.

Martin
__________________
osprey__viper is offline   Reply With Quote
Old 05 January 2005, 18:45   #18
Member
 
Country: UK - Scotland
Town: Ardnamurchan
Make: Domar Corsair
Length: 4m +
Engine: Mercury 20HP
MMSI: What?
Join Date: Aug 2004
Posts: 215
Ive never been to hoorn, but have done some sailing back in the mid 90's around the Afsluitdijk and East side of the ijsselmeer and i have sailed up to 3 of the islands with my daddy....

It was kindoff an holiday.. but sailing is to slow for me.. everything takes to long, is to quiet and you cant really get anywhere instantly without to much hassle of navigating difficult areas (unlike a RIB!)
__________________
Mr-d is offline   Reply With Quote
Old 06 January 2005, 10:29   #19
Member
 
Country: Netherlands
Town: Hoorn
Boat name: skip
Make: revenger 25
Length: 7m +
Engine: mercury 250 pro xs
Join Date: Oct 2001
Posts: 129
same for me

__________________
niels is offline   Reply With Quote
Old 06 January 2005, 10:55   #20
Member
 
Country: Canada
Town: Newfoundland
Length: no boat
Join Date: May 2000
Posts: 2,099
I've been sailing in that area too, as a kid. We had a week from Monickendam (sp) and called into Hoorn. Nice place.
__________________

__________________
Out of the fog......
Alan is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 16:16.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×