Reply
 
Thread Tools Search this Thread
 
Old 22 March 2003, 07:56   #11
RIBnet supporter
 
Brian's Avatar
 
Country: UK - Isle of Man
Town: Peel, IOM
Length: no boat
Join Date: Nov 2000
Posts: 2,277
RIBase
Still nobody has answered my question on these devices.

If they are that good (and certainly everyone seems to agree that they are), why don't the engine manufacturers either build them in, offer them as a model variant or offer the fins as an "extra" when yoou buy the engine?
__________________
Brian is offline   Reply With Quote
Old 22 March 2003, 09:19   #12
Member
 
Country: Other
Make: FB 55
Length: 10m +
Join Date: May 2001
Posts: 1,711
Hmmm, good question Brian. I used them on two of my ribs and they did exactly as it said on the box:
Gets you on the plane quicker.
Positive steering at low speeds.
Assists in maintaining planing at low speeds, and so on.
I suppose it is like anything extra, spoilers on a car to keep force you down (on to the road) at higher speeds etc. If your boat is set-up properly there should be no need for these things, that said, it can certainly enhance performance, BUT does take some speed off your top end due to additional drag.
I do not think Cyanide would benefit from having them
__________________

__________________
Charles is offline   Reply With Quote
Old 22 March 2003, 11:41   #13
Member
 
Country: UK - England
Town: Blackpool
Boat name: To Exi
Make: new sib 4 man
Length: 8+ft
Engine: Mariner 4hp long shaft
Join Date: Nov 2002
Posts: 1,012
Well I was in the yacht club today for my usual lunchtime drink of coffee,discussing nautical matters as usual,When in walked a fellow ribster,who withought any provercation said ,you know I fitted them fins things and they work just great.


So why do they work so well as I am sure like Brian I am thinking if they work on a outboard then why not on a leg.So here is the maybe but dont know thought for today?
Do they opperate like a set of trim tabs ?.
I think they must as they are in a better position than tabs.I dont want to bring the tab question back and it is only a sugestion,but we know they seem to work,So could this be the reason?

If I am correct with this assumption then the larger the boat mybe the larger the fins,It may put extra loads on the trim and tilt motor,as the surfice area is greater?

This is a guestimate only and not a fact.If there is somebody who can tell us exactly why they work so well ,then great.

I am going with Bennet tabs at present but it might be possible maybe to just have some big foils on our single leg that will do the same instead providing our trim and tilt motor doesnt burn out?

Its only a suggestion at this stage So please dont anybody feel offended or upset about it.
__________________
www.eurocommuter.com
crazyhorse is offline   Reply With Quote
Old 22 March 2003, 15:13   #14
Member
 
Country: UK - England
Town: scotland
Boat name: Leviathan
Make: Phantom
Length: 8m +
Engine: GM Diesels
Join Date: Jan 2003
Posts: 1,437
CH

With foils on a single drive instead of tabs, you would get stern lift, but not the benefit of being able to "level" the boat lateraly in a beam sea/wind, which is the main advantage of tabs on a boat like "your's to be".

P.S. like the name says, they are a "foil" or wing section, and get thier lift from this form, not like a tab which is less efficient.
__________________
Jonny Fuller is offline   Reply With Quote
Old 22 March 2003, 15:14   #15
Member
 
Country: UK - England
Town: NW& wherever the boat is!
Boat name: depends on m'mood!
Make: Humbers/15-24m cats
Length: 6m +
Engine: etec130/big volvos
MMSI: many and various
Join Date: Nov 2001
Posts: 1,815
We have had fins on two boats. Our little 4m searider with a 50hp 2 stroke had in its previous life been used by divers carrying heavy loads and came with fins fitted. Now the fins were fine on that but the boat was on the max power allowable and came up onto the plane like a rocket anyway. We also put some on a 15ft fast fishing boat which was a bit underpowered with a 40 two stroke. On that model boat with a manual tilt engine the o/b has to be out one pin past the centre hole to lift the bow with its cuddy or it would handle like a pig. The fins on that boat may have stiffened it up a bit in turns, taking some of the heeling out of it, but they weren't a success otherwise. With the o/b at that degree of tilt I think they occasionally acted like submarine diving planes and gave some strange effects and enough disturbance at times to ventilate the prop. Personally if the boat works without them I would not fit a pair again cos they didn't do the fishing boat any favours.
Why do they work? Theory is I suppose if you look at the leading edge they are an aeofoil shape so they should act as a wing and give lift.
Dave (it was lovely at sea today!) M
__________________
wavelength is offline   Reply With Quote
Old 22 March 2003, 15:47   #16
Member
 
Country: UK - England
Town: Blackpool
Boat name: To Exi
Make: new sib 4 man
Length: 8+ft
Engine: Mariner 4hp long shaft
Join Date: Nov 2002
Posts: 1,012
Well thanks Doods,

Seem good for small boats who want lift,but no good for squaring up to a beam sea,side on.

So i will stay as I was, and not try and reinvent the wheel,

Thanks Wavelength and Mr best behaviour JF

Yes it was a nice sea today of Blackpool W we just bought a 2.6 Maxon sib with a 2hp volvo penta air cooled so whatch out,I may be out there sooner than expected.

__________________
www.eurocommuter.com
crazyhorse is offline   Reply With Quote
Old 22 March 2003, 16:24   #17
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 crazyhorse
Well Thanks W and Mr best behaviour JF
?????????????????
__________________
Jonny Fuller is offline   Reply With Quote
Old 25 March 2003, 06:53   #18
Member
 
Cookee's Avatar
 
Country: UK - England
Town: Salcombe, Devon, UK
Boat name: BananaShark
Make: BananaShark
Length: 10m +
Engine: 2xYanmar 260 diesels
Join Date: Mar 2003
Posts: 4,225
I had some on a 14' Fletcher with a 70 hp Suzuki and it did what it said on the box as well - very much an all round improvement. Used the boat mainly for skiing and no idea what it did to the top speed but it was fast enough!

Read something recently about them upsetting a RIB or 2 but I think they are perfect for boats that maybe a bit underpowered or slow to plane.

Manos - I don't think your 200 hp is underpowered!

Brian - I think they will lower the top speed of a boat - will not suit or be needed on every hull - and may even affect some boats badly!

Trim tabs only work when needed unless they are lowered too much - therefore they will not affect the performance so much as they are not creating so much drag.
__________________
Cookee
Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
Cookee is offline   Reply With Quote
Old 25 March 2003, 07:25   #19
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 Cookee
Manos - I don't think your 200 hp is underpowered!
You are absolutely right!!
I just thought I may get a bit more out of it tha's all.
Any way will not use it for 200.
Manos is offline   Reply With Quote
Old 25 March 2003, 13:34   #20
Member
 
Cookee's Avatar
 
Country: UK - England
Town: Salcombe, Devon, UK
Boat name: BananaShark
Make: BananaShark
Length: 10m +
Engine: 2xYanmar 260 diesels
Join Date: Mar 2003
Posts: 4,225
Manos - 2 reasons I can think of - Firstly the extra drag of something not designed to work with that size of engine and speeds, and you'd probably rip it off the cavitation plate if it wasn't bonded on in some way, which in turn would most likely do more damage - shall I go on?
__________________

__________________
Cookee
Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
Cookee 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 09:16.


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