Reply
 
Thread Tools Search this Thread
 
Old 09 September 2004, 19:07   #1
Member
 
Country: UK - England
Town: Exeter
Boat name: gazza's girl
Make: rib-X
Length: 5.75
Engine: Suzuki 90 4 stroke
Join Date: May 2004
Posts: 80
Low Down on Dol-fins

what is the general opinion with regard to Dol-fins / Stingrays for an outboard.......( Those plastic wing type things)

What are the benifits and the problems.....

Who uses them and why.....

Is it a worthwhile investment......

Any info would be appreciated.....


Regards


Gazza
__________________

__________________
Gazza is offline   Reply With Quote
Old 09 September 2004, 19:08   #2
Member
 
Louise's Avatar
 
Country: UK - England
Town: Reading
Make: None
Length: under 3m
Join Date: Jul 2003
Posts: 2,039
This has been discussed before. Try doing a search on 'Doel fins'. HTH.
__________________

__________________
MUM POWER!
www.biboa.com
Scorpion RIB Group on Facebook
Louise is offline   Reply With Quote
Old 10 September 2004, 03:26   #3
RIBnet supporter
 
Nauti Buoy's Avatar
 
Country: UK - England
Town: West Wittering
Length: no boat
Join Date: Jun 2004
Posts: 1,447
Gazza

I used to have an Avon 5.6m with a Suzuki 90hp 4 Stroke, so very similar to your set up, I found it to be a bit bum heavy and the bow used to lift quite high until you got at any reasonable cruising speeds. So before I took it out again I had some Dol phins fitted and that made a significant difference, it planed a lot quicker and the bow was no where near as high. Also found I could plane at a lower rev limit and stay at that limit. Hope this helps.
__________________
Nauti Buoy is offline   Reply With Quote
Old 10 September 2004, 04:33   #4
tue
Member
 
Country: UK - England
Town: Paignton, Devon
Make: Chinook and Viking
Length: 7m +
Engine: 150 Etec + 125 Merc
Join Date: Jul 2003
Posts: 526
If you will be carrying alot of weight especially at the stern then they are worth considering, as they will help lift the stern and get you on the plane alot quicker. I had them on mine but removed them after I raised the engine as they have been know to cause very dangerous conditions and even turn the boat over because they catch the water and can drag the boat in all sorts of directions
__________________
**Paul**
Brixham BSAC
tue is offline   Reply With Quote
Old 10 September 2004, 05:27   #5
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Hydrofoils

This supports what Tue is saying, solve one problem but cause another. It would be better to get the boat more balanced than fit these things.
Des
__________________
Scary Des is offline   Reply With Quote
Old 10 September 2004, 06:25   #6
Member
 
Country: UK - Scotland
Town: Glasgow
Length: no boat
Join Date: Aug 2003
Posts: 18
From reading the replies and looking at the archive stuff I think you will agree that nobody agrees on Doel Fins.

I have some fitted on a large diesel rib and have only founds benefits so far.

I would get some and try them as I am sure you get a money back promise if you are not happy with them.
__________________
Mark Anderson is offline   Reply With Quote
Old 10 September 2004, 07:16   #7
Member
 
Country: UK - England
Boat name: Seashell
Make: Redbay
Length: 7m +
Engine: Inboard diesel
Join Date: Jan 2004
Posts: 5,263
But you have to drill holes in your engine (cavitation plate) don't you??
__________________
Tim M is offline   Reply With Quote
Old 10 September 2004, 07:19   #8
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Quote:
Originally Posted by Mark Anderson
............I have some fitted on a large diesel rib and have only founds benefits so far...........

With a large heavy boat it is far harder to upset the balance and it has so much momentum that small changes in dynamic load will have little effect, this is not the case with a smaller boat.

On an aeroplane you can perform a roll by lowering a wing, as one wing drops the other raises so the plane rolls. I can see the same thing happening with these fins, especially if you were turning in the same direction as the direction of rotation of your prop. The combined effect would cause the boat to roll around the longitudinal centre of rotation.

I think they are un-safe and it is only a question of when they will fail not a question of if.

I also think that if they are so good why donít the o/b manufactures fit them as standard?
Des
__________________
Scary Des is offline   Reply With Quote
Old 10 September 2004, 08:22   #9
tue
Member
 
Country: UK - England
Town: Paignton, Devon
Make: Chinook and Viking
Length: 7m +
Engine: 150 Etec + 125 Merc
Join Date: Jul 2003
Posts: 526
Quote:
Originally Posted by Scary Des
I also think that if they are so good why donít the o/b manufactures fit them as standard?
Des
Because of the problems with the rolling effect if they were fitted as standard there would be all sorts of problems. Also some boat/engine setups don't require them when some do. Our club dive RIB 5.8m Delta with 90 fourstroke Mariner) would struggle to get on the plane with 6 divers and kit until I fitted hydrfoils. Now it gets up and goes without any trouble. Where as if I fitted them to mine I could end up in real trouble. It all boils down to wether you need them because of planning difficulties or carrying extra weight or wether you want them because they look like they will make you go faster.
__________________
**Paul**
Brixham BSAC
tue is offline   Reply With Quote
Old 10 September 2004, 08:47   #10
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Quote:
Originally Posted by tue
..........It all boils down to wether you need them because of planning difficulties or carrying extra weight or wether you want them because they look like they will make you go faster.
No I think it all boils down to the fact that they are unpredictable in use and as such are dangerous.

If after extensive testing and sea trials an experienced helmsman finds a benefit sure use them. But most people will buy them load their rib with kit and set of for the weekend only finding a problem when they are tipped into the sea. Des
__________________

__________________
Scary Des 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 03:27.


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