Wing keels on catamaran.

[Mix]

Hi guys, I’ve got some issues with the catamaran I bought it’s got rather large mini keels with wings on the back of them there around 350 mil wide.
The wings seem to get damaged easily and I am contemplating cutting them off and glassing them up. I realise these maybe an integral part for the boat when it dries out so the back doesn’t drop down too much but more the point do they serve a purpose for the boat while under sail?

This is not a high-performance catamaran. It’s an IMP 46 footer it may be up in the 8 to 10 t range. I. Those mini keels are about 5 m long which is storage tanks water portside and diesel on the Starboard side

If anyone has some thoughts are much appreciate some advice.

[SailingHarmonie]

Wow...

Those keels are so wide they will stall at any useful upwind angle. They were a way to for the designer to add lots of tankage and not compromise interior accommodations.

I'd be surprised if the wings do anything other than add drag. To be effective, they need to separate the high pressure and low pressure side of the foil where the pressure difference is highest, and that is NOT at the very back of the foil. At higher speeds they MIGHT reduce pitching, maybe...

I don't see where they would affect the behavior of the boat on the hard, unless you chose a place to dry out that consisted of soft mud, but why would you do that?

As for removing them or not... I don't have a recommendation. I don't know the construction details. But I very much doubt you would notice a difference in sailing performance. I suspect this boat was built when winged keels were all the rage and every cool boat had to have them.

[Franziska]

I would think their primary purpose is to provide a decent stance when drying out on a beach.
Fine tipped keels tend to sink in on this occasionally. Soft sand is but one example.
Sinking in can cause problems on some bow or stern heavy boats... .

I know of many multihull sailors drying out occasionally on beaches. We do it too when in tidal waters. It's a great experience and, occasionally one can do maintenance too.

[Divemasterflipp]

Hi Y'all

[Sailorman Ed]

Look to be very blunt leading edges. Is the tankage in the "winged" portion too?

[Mix]

Thanks for all your speedy replies. I wish my boat was that fast.
The tanks don’t go down into the winged portion of the keels.

The wings are basically attached just with resin and Bog, which makes them break, rather easy, even on the jinka.

Since I have a bunch of repairs to do sorry, I didn’t include them in the pictures I am considering cutting them off and starting fresh.

[chrisr]

definitely there to provide wider base when drying out on a beach...save sinking into the sand too much

quite useful (ask me how i know !)

cheers,

[smj]

I worked for a custom catamaran builder about 25 years ago and he took on 2 projects where the owners wanted or needed shallower draft. He cut the keels down and added wings to the back of mini keels if I remember correctly. The thought being they would help with lift and pointing ability. Did they work? I have no idea. Here’s an article discussing some of the benefits of wings on keels. I believe the article focuses on monohulls but wonder if some would also hold true for catamarans.

https://www.riggingdoctor.com/life-a...tip%20vortices.

[longjonsilver]

Were wings not "invented" to get the ballast lower in the water without deepening the draft? But catamarans don't have ballast, so the aforementioned answers about sinking into the sand cud be the only real "reason" for their existence imho. i'd be tempted to cut them off.

jon

[smj]

Originally Posted by longjonsilver

Were wings not "invented" to get the ballast lower in the water without deepening the draft? But catamarans don't have ballast, so the aforementioned answers about sinking into the sand cud be the only real "reason" for their existence imho. i'd be tempted to cut them off.



jon

Not according to the article above