Whale tails and such for small outboards - Page 2

menzies · 03-23-2018, 08:44 AM

The tender on Sonas came with them. I am not sure of the value since it is an 11 RIB with a 25hp four stroke Yamaha, which I feel would not have an issue with getting on plane anyway.

However, after a couple of years of use I have found one disadvantage and one advantage.

The disadvantage is that when you are coming off the back of a wave or, more usually, a wake, the fin can make you broach because one side is digging in while the other is catching air. This is even when throttling back and taking it easy.

The positive I found out when I struggled to get back onto the RIB from the water. You can use the fin as a step plate so long as you are careful to put as much of your weight on the engine or transom/tube as you can, so as not to snap it off. I have recovered wife and guests that way where I have their arm.

Cruzer · 03-23-2018, 09:09 AM

I have been having a very hard time locating a fin for my 25hp Yamaha. Any suggestions on where to find one?

Mr. Blu · 03-23-2018, 10:51 AM

Quote:

Originally Posted by silver lining1

The smart tabs work very well. Need to get the correct size and force. My 11.5 Achilles with a 30 hp jumps right on plane solo. The tabs also help the dinghy plane at lower speeds. The only downside is they need repair every couple years but I will always use trim tabs if possible

What happens to them that you have to repair them every couple of years?

menzies · 03-23-2018, 12:09 PM

Quote:

Originally Posted by Cruzer

I have been having a very hard time locating a fin for my 25hp Yamaha. Any suggestions on where to find one?

I just looked. The brand name on mine is Hydro-Stabilizer.

Simi 60 · 03-23-2018, 02:34 PM

Quote:

Originally Posted by Cruzer

I have been having a very hard time locating a fin for my 25hp Yamaha. Any suggestions on where to find one?

Simple
5 seconds and you dont even have to get in the car.

https://www.ebay.com/itm/8-30HP-Yama...-/272789918371

silver lining1 · 03-23-2018, 07:56 PM

Quote:

Originally Posted by Mr. Blu

What happens to them that you have to repair them every couple of years?

twice in five years I have had to replace a pressurized cylinder that provides the trim tab force. These are like hatch cylinders but enclosed in a "water proof" rubber housing. And just last week I noticed my 5 year old smart tabs have a trim tab that the hinge is starting to fail. But, they work so well for a reasonable price on my dinghy, that I am still happy

Mr. Blu · 03-24-2018, 03:20 AM

Quote:

Originally Posted by silver lining1

twice in five years I have had to replace a pressurized cylinder that provides the trim tab force. These are like hatch cylinders but enclosed in a "water proof" rubber housing. And just last week I noticed my 5 year old smart tabs have a trim tab that the hinge is starting to fail. But, they work so well for a reasonable price on my dinghy, that I am still happy

Thanks for your explanation.
I think that the force on the smart tabs and the cilinders is pretty big. But I think that this will even more apply for the fins. Per square inch of fin the force must be enormous if you take into account that it has to lift up stern and engine.

A lot of opponents to fins say that they don't like drilling into the cavitation plate (but that issue can be avoided with fins that use other systems of fixing) but they also say that a fin can damage the stern, due to the upward force to the fixing bolts of the engine. But I have never heard that using the fin actually has damaged the boat or was the cause of an accident.

The smart tabs and cilinders are constantly working and correcting, where as the fin only has to work until the boat is plaining. But I am not an expert. And after all: boats cost money

Cruzer · 03-24-2018, 08:07 AM

Quote:

Originally Posted by menzies

I just looked. The brand name on mine is Hydro-Stabilizer.

Quote:

Originally Posted by Simi 60

Simple
5 seconds and you dont even have to get in the car.
https://www.ebay.com/itm/8-30HP-Yama...-/272789918371

I thank you both!

drillguy · 03-24-2018, 09:14 AM

I went with the smart tabs 2 years ago. I have a 9.5' aluminum rib with a 9.9 outboard. I have the 20# actuators and the set up works well. The only downside I can think of is that when beaching the dinghy, we have to lift the stern up off the sand to drag it back into the water or spin it around and pull it forward (like if the tide goes out and leaves the dink 30' up the beach) I suppose that if it bothered me enough I could attach a light chain to the tab that I could lift them and hook to an attachment point on the transom.
I have a friend that has a 12' rib that had no problem getting up and out of the water but porpoised a lot when running. No adjustment of trim would help. He put a set of smart tabs on it and they cured it.

Maerin · 03-24-2018, 04:59 PM

Quote:

Originally Posted by Cruzer

I have been having a very hard time locating a fin for my 25hp Yamaha. Any suggestions on where to find one?

Doel-Fin will make a huge difference. I have one on my 15 HP Yamaha, made a dramatic difference in how it planes and general stability. Took all the squirreliness out of the dink and it pops on plane. Highly recommend, not hard to install. Wouldn't be without them.

I've had experience with the mini-trim tabs on a friends boat, I was asked a number of times to repair them, seems they never lasted even a season, and when they didn't work (which was most of the time) the dinghy was a slug.

Cruzer · 03-24-2018, 06:48 PM

Quote:

Originally Posted by Maerin

Doel-Fin will make a huge difference.

Thanks so much Steve. At $26 (this weekend) it's certainly worth a try!

Antares · 03-27-2018, 11:51 AM

Thanks to all for sharing your experiences. I've ordered a shark fin classic jr. and will try it first. If more remedy is needed a tiller extension will be added. Due to mounts for dinghy wheels there isn't room on my transom for smart tabs but it sounds like the need for maintenance and repair is higher than I care to take on.

Mr. Blu · 03-27-2018, 02:06 PM

Tomorrow I will put my Attwood Gull wing on my dinghy.

Cruzer · 04-08-2018, 11:46 AM

Quote:

Originally Posted by Maerin

Doel-Fin will make a huge difference. I have one on my 15 HP Yamaha, made a dramatic difference in how it planes and general stability. Took all the squirreliness out of the dink and it pops on plane. Highly recommend, not hard to install. Wouldn't be without them.

Finally got the Doel-fin on the 25 HP Yamaha and while I haven't yet run it through the gamut of tests I intend to, it instantly improved the performance and running attitude of the tender with no ill effects that I've noticed. Not too terribly hard to install although not without a challenge or two. And now removing the zinc on the cavitation plate would require removal of the fins, although it's not a zinc that gets much of a workout as it's out of the water other than when the tender is being run.

Thanks again for the great suggestion!

MVDarlin · 05-10-2018, 12:35 AM

Quote:

Originally Posted by Antares

I'm hoping to get the benefit of the collective experience of the group on the benefit of using a whale tail on the cavitation plate of my tenders outboard. The problem I'm trying to cure is an extreme bow up condition when accelerating to a plane. The dinghy is a WM hypalon 3.10 rib with a 9.9 Mercury 4 stroke. The motor is set at the lowest position (bow down) possible. Even with that keeping the bow from pointing at the noon sun requires my arm on the tiller stretched out straight and my ample center gravity as forward as I can reach. Once on plane and the bow comes down things are ok. With two people the boats behavior is more civilized.

Would one of the whale tail devices help in this situation and if so, which of the several brands have you experienced satisfactory results?

Add dole fin to outboard. Move fuel/ battery fwd.

Mr. Blu · 05-10-2018, 03:10 AM

The Attwood Gull fin doesnot do the job. ( However it looks " cool")
I will go now for the smarttabs. But I do not know where to buy them in Croatia so I will have to wait until I will get back in the Netherlands.

**Shrew** · 05-10-2018, 01:06 PM

The problem with any foil that you attach to the lower unit it, you are now introducing lift via the outboard. This is transferring force to the transom vertically at the engine mounting bolts. For most dinghy's these are just screwed tight and not through bolted.

Ideally, the boat should be planing as a result of lifting forces on the hull. Trim tabs and proper trim through load distribution is the better solution IMHO.

MVDarlin · 05-10-2018, 01:28 PM

Quote:

Originally Posted by Shrew

The problem with any foil that you attach to the lower unit it, you are now introducing lift via the outboard. This is transferring force to the transom vertically at the engine mounting bolts. For most dinghy's these are just screwed tight and not through bolted.

Ideally, the boat should be planing as a result of lifting forces on the hull. Trim tabs and proper trim through load distribution is the better solution IMHO.

Mine really helps my boat plane and stops proposing. I have an 11 ft whaler with 15 hp Honda.