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Hydro Fin Size for 13' Sport 40HP
Allan_in_SoCal	#1  Posted on 02/08/08 - 9:31 AM
Member Posts: 5 Comments: 1 Joined: 11/06/07	I have fitted out a 13' Sport for coastal scuba diving. It's worked great, except for the amount of bow rise that occurs between idle and planing. I'm told this is normal for 13's. People have suggested that I add a fin on the anti-cav plate to help the boat stay level as it transitions to plane. The engine is 40HP two stroke Suzuki.... Question is... how big of one should I install?? Any ideas out there?? The various brands usually carry two sizes... big and small. 40 HP is the break point between the sizing. The big looks really big, as in good up to 225 HP. But the small looks, well, small. Thanks for any an all ideas! Edited by Allan_in_SoCal on 02/08/08 - 4:33 PM
Joe Kriz	#2  Posted on 02/08/08 - 11:33 AM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	I don't think you have a choice on what size you can buy. You just need one that is designed to fit your size of engine meaning that you would buy one for the Suzuki 40 hp. There are different brands. Maybe others here will give you their opinion on what brands they prefer.
ioptfm	#3  Posted on 02/08/08 - 6:32 PM
Member Personal Page Posts: 1533 Comments: 3 Joined: 10/28/06	Allan, I put one on my 15' and it made all the difference in the world at low idle speed and popping out of the water. It should be marked on the package what size motor each one is compatible with. If I'm not mistaken, the spacing of the bolts on cav plate will dictate what size you will need. Tom 1979 Sport 15'
David1877	#4  Posted on 03/12/08 - 9:38 PM
Member Posts: 6 Comments: 0 Joined: 03/11/08	My brother has a 13 powered with an Evinrude 40. He put on a fin to address a similar issue. He liked it until the boat caught some air and threw him overboard dislocating his shoulder. Occurred without warning. Get the smaller one just in case. I had a Daunt 13 with a 40 and I found a stainless prop helped considerably with hole shot.
CES	#5  Posted on 03/13/08 - 4:52 AM
Member Personal Page Photo Albums Project Albums Posts: 2681 Comments: 7 Joined: 04/27/07	A stainless prop helped my hole shot as well. My boat practically jumps out of the water if I gun it from a stand still. With my old aluminum prop, the boat wasn't as responsive. SS props do make a huge difference. Cliff 1966 13' Sport with a 1993 40hp Yamaha 2 Smoker
svwalkabout	#6  Posted on 03/13/08 - 7:44 AM
Member Personal Page Posts: 11 Comments: 0 Joined: 09/05/07	For what it is worth, my vote is for Smar Tabs. I have a 1969 13 with a 25hp Honda pushing a 12 pitch prop at 5000' altitude and the difference is night and day. Previous to the Smart Tabs, the bow would go sky high and struggle to plane. Understand that at my altitude, I have lost roughly 15% from the motor due to the thin air. After I took 30 minutes to install the tabs, I had an entirely different boat. Check out SX Smart Tabs I put the SX9510-30 on my 13 and am very impressed with their performance. Currently with the Honda 25 and 12 pitch prop at 5300 rpm I top out at roughly 24 mph on the speedo. Don't hesitate to call Nauticus and talk to Jeff. He answered all my questions and gave me some additional tips as well.