Reply
 
Thread Tools Search this Thread
 
Old 18 April 2004, 10:37   #1
RLS
Member
 
Country: UK - Channel Islands
Town: St.Helier
Make: Rib-X
Length: 6.4m
Engine: Outboard 200 Merc Optimax
Join Date: Dec 2003
Posts: 29
6.5m Top Speeds????

Hi all,
To all those owning or have been on a rib around 6.5m before...I am interested to hear the top speeds of various makes and models of Ribs out there. Please can you let me know what make of rib and what engine yours has and what top speed you have reached - and if you have the dead rise angle that would be interesting too!!
Thanks in advance everyone.
__________________

__________________
RLS is offline   Reply With Quote
Old 18 April 2004, 11:35   #2
Member
 
Country: UK - England
Town: Portsmouth
Make: Tornado
Length: 6m +
Engine: Yamaha HPDI 200
Join Date: Jan 2003
Posts: 323
Send a message via MSN to thorper
We've seen 53mph on the GPS flat out. Engine is Yamaha HPDI 200hp, hull is tornado 6.8.

No idea about the deadrise angle though.

Ricky
__________________

__________________
thorper is offline   Reply With Quote
Old 18 April 2004, 11:59   #3
RLS
Member
 
Country: UK - Channel Islands
Town: St.Helier
Make: Rib-X
Length: 6.4m
Engine: Outboard 200 Merc Optimax
Join Date: Dec 2003
Posts: 29
Tornados have a very deep V is this correct? Making them great in the rough I presume!!
__________________
RLS is offline   Reply With Quote
Old 18 April 2004, 14:06   #4
Member
 
Country: Sweden
Town: Stockholm
Boat name: Osprey & Ring
Make: Osprey & Ring
Length: 9m +
Engine: Plenty
Join Date: Mar 2003
Posts: 860
Had a Osprey Seaharrier (6,6m) before with a Yamaha 200HPDI, changed gearbox on that one to a 150VMAX gearbox to get the duoprop.
Lost 1 1/2 knots but got a fantastic grip, boat made 51,6 knots on GPS.
__________________
www.grandrib.se
Petrov is offline   Reply With Quote
Old 18 April 2004, 15:40   #5
Member
 
Country: UK - England
Town: London/Hamble
Boat name: Hot Mustard
Make: BWM
Length: 6m +
Engine: Mariner 90
Join Date: Apr 2004
Posts: 124
Forgive my ignorance, but what is deadrise?
__________________
Bajan is offline   Reply With Quote
Old 18 April 2004, 15:48   #6
RIBnet supporter
 
nugent's Avatar
 
Country: UK - England
Town: Bromsgrove
Boat name: Kick-Ass !
Make: PAC/Artic 22
Length: 6m +
Engine: 250hp Yamaha
Join Date: Nov 2003
Posts: 3,385
6.2mtr widebody ribcraft 135hp optimax showing 46 on gps// 60mph on guage
__________________

MY BIGGEST WORRY IS THAT MY WIFE(WHEN I"M DEAD)WILL SELL MY TOY'S FOR WHAT I SAID I PAID FOR THEM.
nugent is offline   Reply With Quote
Old 18 April 2004, 16:19   #7
Member
 
Country: Greece
Town: Gloucetsreshire
Boat name: GATO DI MARE
Make: MAR.CO
Length: 9m +
Engine: Yamaha 200Vmax
MMSI: 235027678
Join Date: Sep 2002
Posts: 3,339
Send a message via MSN to Manos Send a message via Yahoo to Manos Send a message via Skype™ to Manos
Quote:
Originally Posted by Bajan
Forgive my ignorance, but what is deadrise?
Since none of the 'experts' know what deadrise is I will enlighten the forum:

Bow deadrise
Deadrise is the angle of the boat's bottom to the horizontal. It is measured at both the bow and the transom. Knowing a boat's bow deadrise gives a feel for its seakeeping abilities. For example, a boat with a generous deadrise angle at the bow, maybe 60 degrees, will cut deeply into a sea as the bow drives downward. Imagine a knife cutting through butter. The sharp edge goes through easily, but the wide, flat side mashes the butter. A compromise is a wedge shape where the wider the wedge gets the less the knife penetrates. A boat's bow is similar to the wedge shape, which stops it from going too deeply into the water. When a boat has to drive into large waves, bow immersion is resisted by a large, flat chine (as shown here) and flared bow sections above the chine (as seen on a Carolina-style hull). A boat with low deadrise at the bow will plow through waves and slam.

Stern deadrise
Deadrise varies over the length of the hull. However, it is generally accepted that if the deadrise remains fairly constant from station six to the transom, lift is appreciably greater and drag is reduced. If the transom deadrise of this boat is 14 degrees. Deadrise gives the boat directional stability and reduces wetted surface as the boat rises onto a plane.

In rough terms, boats with:
transom deadrise angles of 0 to 5 degrees are better in flat waters
transom deadrise angles of 5 to 10 degrees generally stay close to shore
transom deadrise angles 10 to 19 degrees combine good seakeeping, fuel efficiency and speed in waves (think sportfishing boats)
transom deadrise angles greater than 19 degrees tend to be high-speed deep-vee craft
In general a lower transom deadrise angle results in a boat that is easier to get on plane and is very stable when stopped. However, it will have poorer seakeeping abilities when powering into a seaway. Boats with deadrise angles greater than 20 degrees generally perform best in a seaway, but they also tend to roll when stopped.

In conclusion then, deadrise is the angle of a boat's bottom relative to the horizontal, and is measured at the boat's transom to determine the "V" of the boat. Modern "Deep V" boats have more than 20 degrees of deadrise, "Modified V's" have more than 15 degrees of deadrise, and "Semi V's" have 12 or more. It gets confusing because as new designs come out with deeper hulls, the definition shift. Some years ago 18 degrees was considered a real deep V. Now 24 or 25 degrees is a real deep V and 18 degrees is a modified V. A deeper V takes more power to get on plane, and usually pounds less in rough seas at speed. A deeper V is often less stable at rest, like when drifting, and has different handling characteristics at all speeds than a shallower V hull of the same length.

Hopefully the forum 'experts' will add and elaborate on my comments
Manos is offline   Reply With Quote
Old 18 April 2004, 16:45   #8
Administrator
 
John Kennett's Avatar
 
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 6,830
Quote:
Originally Posted by Manos
Hopefully the forum 'experts' will add and elaborate on my comments
You haven't made any comments -- you just cut and pasted someone else's comments! Why not just post the link instead?

John
__________________
John Kennett is offline   Reply With Quote
Old 18 April 2004, 16:48   #9
Member
 
Country: Greece
Town: Gloucetsreshire
Boat name: GATO DI MARE
Make: MAR.CO
Length: 9m +
Engine: Yamaha 200Vmax
MMSI: 235027678
Join Date: Sep 2002
Posts: 3,339
Send a message via MSN to Manos Send a message via Yahoo to Manos Send a message via Skype™ to Manos
hmmmm u R right is from a book but are my comments cause I wrote them
Manos is offline   Reply With Quote
Old 18 April 2004, 20:01   #10
Member
 
Country: UK - England
Town: Midlands
Make: Nautique
Length: 6m +
Engine: PCM 5.7l
Join Date: Oct 2003
Posts: 1,082
Are you not confusing transom deadrise with the hull deadrise at the transom?

Transom dead rise is the angle of the transom to the vertical. Most boat builders build in a 12 degree transom deadrise to enable the engine/leg to be more effective at pinnign the bow down when trimmed in.
__________________

__________________
simmons0 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 14:07.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.