Whale Tail Thoughts

[bay5884]

Does anyone have any thoughts on these aluminum plates? Pros and cons? I have one on a 14 ft bayliner with a 50hp force that I recently bought, and am considering taking it off. It's easy to see that it's very effective as far as keeping the boat planed out, but if I do say a slow figure eight, the prop comes right up out of the water. Normally, without the tail, the bow would be up high enough to prevent this. Any thoughts welcome!

 

[walleyehed]

Re: Whale Tail Thoughts

Normally the fin should HELP in turns but what I suggest is clicking the "SEARCH FORUMS" tab and entering hydrofoils or whale tails. You should get some good info there........

 

[SeaHorse]

Re: Whale Tail Thoughts

I recently added Nauticus Smart tabs and got rid of my motor mounted fin. Great improvement. More speed, planes at slower speed, etc. just like they said.

 

[walleyehed]

Re: Whale Tail Thoughts

Seahorse, I can't say I know much about the "TABS", but one of the reasons I like a fin is because in the waters I fish there is a load of standing timber, and if, while fishing with your trolling motor, you happen accross a tree, the fin deflects the tree around your lower unit/prop. Also, when backing out of the timber, I have my engine tilted up till the prop is at the surface, and once in awhile you will bump trees with the back of the boat. will the trim tabs stand much stress in this area????<br /><br />Bay5884, the operation without the fin does not raise the bow, it lowers the stearn. The fin was actually lifting your rear, but if Ventalating in the turn, I have to wonder if maybe you are slightly under-powered and don't have the leverage to lift the bow....This could simply be a trim issue as well.........

 

[johnfjensen]

Re: Whale Tail Thoughts

"a slow figure eight, the prop comes right up out of the water" is indeed strange. Are you sure the hydrofoil is the cause?<br /><br />I purchased the Permatrim hydrofoil (from New Zealand) and was so impressed I have become their USA dealer/distributor. Thus far no customer has been dissatisfied.

 

[Ralph 123]

Re: Whale Tail Thoughts

Those Permatrim look like bennet trim tabs but fit on the I/O very different from stingrays or Doelfins. How do they compare? Why is that design better? They are very expensive...

 

[Jdeagro]

Re: Whale Tail Thoughts

Bay5884<br /><br />Cavitating in turns is usualy caused by the boat laying over hard with the bow too far down and the stern lifting. This can be caused on V bottom boats when a large hydrofoil lifts the boat from the center (motor), facilitating a teeter totter effect. When the focal point of the boat lift is in the center (V) the boat, it becomes suseptable to listing, especially at crusing or high speeds.<br /><br />Ask the motor manufacturer why the motor does not have a larger cavitation plate.

 

[walleyehed]

Re: Whale Tail Thoughts

nautijohn, have him ask also why they made the cav plate 2-7/8" wider in 92, and why they made it another 3/4" wider in 1996-on..?????

 

[walleyehed]

Re: Whale Tail Thoughts

To my previous post.....I'm talking about J/E...

 

[Jdeagro]

Re: Whale Tail Thoughts

Walleyehead;<br /><br />Good Question! I suspect cavitation plates are part of the prop fuction and design, and should be coordinated to provide the same water density above the prop as below to maximize thrust. I do not think they are ment to be a planing device.<br /><br />I think hydrofoils provide some benefits, but they can also create handling issues on some boats.

 

[Ralph 123]

Re: Whale Tail Thoughts

This is the response I got back from permatrim when I asked the difference between hydrofoils and their product:<br /><br />The permatrim works differently to the Stingray , doelfin and SE 300 hydrofoils, by using the water that comes of the top of the propeller (the<br />hump you get out the back of the motor) and holding that down so you get more lift and thrust from the same amount of power.The other brands work like a aircraft wing, where the water rushing over them gives you lift.<br /><br />The tests done in NZ & Australia rate the permatrim with more lift and better performance all round.A good test done over here was when the water taxi's where using the SE 300 sport and still couldn't get on the plane when fully loaded with passengers, then we fitted a permatrim and they planed easily, they said that they payed for themselves within a week. The taxis are 28 foot rigid inflatables running single 200hp yamahas, carry 16 people.<br /><br />They are also stronger and more durable and can be used for a step.<br /><br />If you need any more info please email me at<br />permatrim@nznet.gen.nz