| Author |
Message |
    
John McGrath
Member
Username: johnkillcare
Post Number: 44
Registered: 04-2008
| | Posted on Monday, January 25, 2010 - 12:11 am: | 
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Had my boat 3 years now, (5.3 mtr Whittley Cherokee v6 mercruiser, Alpha one)It had a hydrafoil (whale tail) fitted when I bought it. It had always felt a bit unstable when turning hard at high speed. After reading some negative comments on this site about whale tails I decided to remove it to see what difference it made. Took the boat out today and what a difference!! The boat is now extremely stable at speed, turns better, feels a lot smoother and gets up on the plane just as easy as it did with the whale tail fitted. Just thought I would let everybody know, if they have one of these things fitted take it off and throw it away, you will be amazed at how much better the boat feels. |
Kghost
Senior Member
Username: kghost
Post Number: 1210
Registered: 07-2008
| | Posted on Monday, January 25, 2010 - 06:23 am: |
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The use of a "whale tale" is a common fix for a under powered or incorrectly propped boat.
In some very rare cases it can be a helpful addition but back in the '90's Merc released a bulleten discouraging the use of these on there products. It would nullify warrenty if used on a boat under warrenty.
They can be very dangerous at high speeds especially if the hull design is so so.
If you need a better hole shot the correct way to achieve this is change the prop pitch down or a torque shift prop. |
Chris Richards
Member
Username: bigblock4banger
Post Number: 93
Registered: 07-2007
| | Posted on Monday, January 25, 2010 - 09:42 am: |
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I had the same experience with my 18' bow rider a few years back. It had a merc 170 I/O and would reach speeds of 45 MPH. .Definitely unstable at higher speeds. After some research,I learned that the foil will lift the drive and boat at its Center of Gravity (CG) --Its like your boat balancing on a tip of a pencil.It did however keep the bow down during the transition from displacement speed to planing speed.
After I tossed the foil, I installed 'Smart Tabs'--They are automatic trim tabs.--Perfect for a boat under 20' |
Kghost
Senior Member
Username: kghost
Post Number: 1212
Registered: 07-2008
| | Posted on Monday, January 25, 2010 - 09:51 am: |
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You are correct with your point, The foil keeps the bow down at higher speeds unlike without the foil less of the hull is in the water. Having the extra hull in the water stresses out the steering at high speeds. You are now trying to turn more of the boat at high speeds. Does that make sense? |
Jasson Thomley
Member
Username: jthomley
Post Number: 47
Registered: 04-2009
| | Posted on Tuesday, February 02, 2010 - 05:27 am: |
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kghost is exactly right on this one!
I went from a three to four blade prop, and changed the pitch, removed the foil I had and the difference was so much better. Much quicker to plane. |
Ken R
Member
Username: ken_r
Post Number: 51
Registered: 06-2008
| | Posted on Tuesday, February 02, 2010 - 04:18 pm: |
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Put the SE Sport 300 Hydrofoil on my boat a couple of years back...awesome! No change in top end, much better hole shot, able to plane at lower speed for wakeboarding and no cavitating. Only downside is slightly stiffer steering at high speeds. 17' Runabout with 3.0 Merc. |
Kghost
Senior Member
Username: kghost
Post Number: 1254
Registered: 07-2008
| | Posted on Tuesday, February 02, 2010 - 06:18 pm: |
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Ken
That is what the foils do. BUT the steering issue is the problem. It also takes a toll on the gimbal ring due to added stress...just so ya know...
When a steering system starts to wear and a foil is on the outdrive and there is excessive slop in the gimbal ring, at high speeds when turning hard one way or the other it becomes very difficult to overcome the forces created by the foil and this becomes a potental danger especially if no power steering is there.......
The gimbal ring is what turns the outdrive left and right when you turn the steering wheel. |
