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Re-powered Dauntless 18 with "whale fin"
jhabernathy	#1  Posted on 05/04/10 - 10:50 AM
Member Posts: 5 Comments: 0 Joined: 05/02/10	In 2008 I purchased a 2000 18' Dauntless that had been re-powered with a 150hp 4 stroke yamaha by the previous owner. It came with a "dolphin fin or whale fin" mounted on the engine. After reading several posts discussing the "dolphin fin" I have the following question: Should I remove the fin? Thanks.
CES	#2  Posted on 05/04/10 - 12:02 PM
Member Personal Page Photo Albums Project Albums Posts: 2681 Comments: 7 Joined: 04/27/07	I would take it off if it were me. A 150 on an 18' is a lot of motor. If the fin is on the boat to help with porpoising, I'd look into using Smart Tabs. The Smart Tabs have been talked about a lot on this forum. Just do a search for Smart Tabs and you'll see what I mean. Cliff 1966 13' Sport with a 1993 40hp Yamaha 2 Smoker
HarleyFXDL	#3  Posted on 05/04/10 - 12:08 PM
Member Personal Page Project Albums Posts: 917 Comments: 30 Joined: 07/24/07	The fin is masking a problem, not fixing it. I would remove it and see what occurs. Kevin 1988 11' Super Sport, 1987 Johnson 15hp. If you think education is expensive, try ignorance "Vegetarian - old Indian word for bad fisherman."
MW	#4  Posted on 05/04/10 - 2:33 PM
Member Personal Page Posts: 1827 Comments: 10 Joined: 01/08/06	Something like that is usually a "Band aid" for a problem Matt
John Fyke	#5  Posted on 05/04/10 - 2:46 PM
Member Personal Page Posts: 1307 Comments: 0 Joined: 09/06/06	I can't see how you need it. Are you having any problems? It would be nice to see how the motor is mounted on the transom. High? Low? Either one of those could give you problems.
way2goofy	#6  Posted on 06/04/10 - 8:26 PM
Member Personal Page Posts: 28 Comments: 0 Joined: 04/26/10	My BIL has a whale fin on his boat. If he has the motor tilted for shallow water the fin gives him no steering control. We go through a narrows with ;ots of VW sized boulders under water in Canada. My Sport 15 with the motor tilted rig-zags right through. His boat is worthless trying to get through. I've told him many time to just get rid of the fin.
joninnj	#7  Posted on 06/04/10 - 10:37 PM
Member Personal Page Posts: 408 Comments: 3 Joined: 06/07/07	I think you get the general idea from the other posts about the Fins... I have been boating a long time and I see many people using these on boats with fairly significant HP, stern drives and outboards. Personally (from experience) I only see use for these on smaller boats with lower HP... They do help. But on larger boats with more engine and power trim... very little value. The trim systems can compensate for all the lift you may need. Another point is that these fins will create drag and catch weeds. Good luck on you new boat!!! Edited by joninnj on 06/04/10 - 10:38 PM Jon in NJ Many other boats and outboards in my boating history The Whaler is the one I like the best!!!
Phil T	#8  Posted on 06/05/10 - 5:07 AM
Administrator Personal Page Personal Album Project Albums Posts: 6991 Comments: 6 Joined: 03/26/05	J - There are many opinions on the benefits of a "whale-tail" device on the anti-cavitation plate. Generally speaking, they are designed to lower the speed at which the boat planes. The early year models of the Dauntless 180 had a notched hull. Does your boat have this feature? A notched hull did have a noticeable bow rise. The hull design was changed at some point in 2000-2001. Are you pleased with the boat's current performance? What mounting hole is the engine bolted to the transom? How many open holes are there on the top set (count down from the top)? What make and model propeller is on the motor? What is the wide open throttle RPM's? If you are not sure of the benefits to your boat from having the whale tail, I suggest you note the boat's performance and planing speed and then remove it and re-test (with the same gear, passengers). Edited by Phil T on 06/05/10 - 5:08 AM 1992 Outrage 17 I 2019 E-TEC 90, Viper 17 2+ 2018 Load Rite Elite 18280096VT
Bake	#9  Posted on 06/05/10 - 4:47 PM
Member Personal Page Project Albums Posts: 902 Comments: 8 Joined: 01/30/06	sounds like most folks have no use for tail fins. I am usually in the same category. Howerver I also realize like it or not they add benefit to boats in regards to lift. I own a 17 EdgeWater (for sale) With a 100 hp Mecury. This boat just felt heavy in the water. I felt there were a number of fixes for the boat. The first thing would have been to add about 15 horse power. second would have been trim tabs, or smart tabs. Knowing I hope to sell the boat soon I opted for the whale tail. For under forty bucks I got the lift the boat needed. It plains better, but most important it stays on plain at lower speeds. This makes a much nicer ride in choppy water. All that said all who think tails are patches for other problems have a valid point but 40 bucks is pretty cheap compared to other solutions. As to your Dauntless with a one fifty. I doubt you need it. take it off and fill the holes with jb weld or something and run it. I bet you will find it runs out great without the tail. Edited by Bake on 06/05/10 - 4:51 PM
jhabernathy	#10  Posted on 07/19/10 - 8:27 AM
Member Posts: 5 Comments: 0 Joined: 05/02/10	Thanks for all of your great advice. I was finally able to get out and test the boat. At WOT the engine turns 5600 RPMs which seems appropriate. We live in an area where the harbor chop can be 2-4 feet. It seems like the whale fin allows me to push the bow down a little better when dealing with oncoming swell. Given lack of performance degradation and maybe a little help with the bow, I am going to leave it on.
mavenmatt	#11  Posted on 07/19/10 - 8:08 PM
Member Posts: 7 Comments: 0 Joined: 05/25/10	How about u take some measurements, time to plane, top speed at what rpm, lowest plane speed, steering abilities and then remove it and remeasure. I'd love to know the difference. I am thinking about getting one and would love some facts!!! whale on!!