H37C "flappers".

[Ed Schenck]

Or alias "zebra mussel collector". On the post entitled "Rudder Post Leak" we were reminded by Gene Greunder about those external deflectors around the rudder post. That water can get into the H37C around the screws. The screws go through the fiberglass into a void. On my boat that is the only place I find zebra mussels at haulout, thick behind those "flappers".Those flappers have a function and I would love to know what the architect knew. Would that be John Cherubini Sr.? Or did someone else draw that up?They must improve water flow around the rudder. But to what extent? How many of you H37C owners still have them? The one likely place for water ingress into the rudder is where the post enters the rudder. These deflectors do prevent "forced" entry. Is this important? Anyone have any ideas? Is JC II aware of these?

 

[Alan J]

Cure

While I whink the flappers are designed to improve water flow around the upper rudder I have always been troubled about the screws into the void and the breeding colony it encourages. While I dont have a solution to the screws, I have stopped the nursery. I spray the area with outdrive clear botton paint just before launch. It is the same spray I use on my shaft and prop. It does a GREAT job of preventing growth.

 

[Ed Schenck]

Thanks for the tip Alan.

I'll give that a try. Meanwhile that void is not too difficult to fill. I made a template by balling up some newspaper with aluminum foil. I stuffed it down in there(the screws were out) to get the right shape. Then I duplicated it with a piece of 2"x6" lumber. It's an odd shape and hard to get a good fit. So I poured a heavy mix of epoxy over it to fill any little gaps.

 

[OBX Sailor8569]

I removed mine!

I removed mine a few years ago during a haulout. I filled the screw holes with epoxy and faired them because of the growth problem. No problem now because the area is easy to clean.OBX SailorS/V BAD BOYOBX,NC

 

[Jerry]

"Flapper" picture

Just happen to have a picture. Note I still have them on the boat...

 

[Don Prior]

Mine leaked

Ed.I had the same problem. After a repair facility replaced one of the "flappers" one of the screws came out leaving a hole into the bilge. I left it for the season and then added a more secure screw and epoxied it in place. It is an impossible place to get to on the inside. I like your idea of a plug to fill the area. I think I will try it with a carved foam block soaked in epoxy.What if there is a leak into a wooden block secured behind epoxy? Would that cause problems? Rot, smell, etc.I guess the easy solution would be to remove them but I have kept the boat original for 21 years now and I hate to give up.Fair winds.Don

 

[Ed A]

ok a good fix might be

Make up some light putty, use micorbaloons to fill the epoxy and you get a very light weight filler and just pour it in. it will fill the void and not allow any water. its a good thing!The deflectors are better than you think, the idea is to keep laminar flow on the top of the rudder the smoother the transisiton is between the hull and the rudder. There is a reduction in drag too but it is probably not a lot. But guys who are concerned about tenths of a know will always have them on. they too are a good thing.

 

[Ed Schenck]

Flapper picture.

Finally, a good "flapper" picture. Could you paint the deflectors a different color Jerry? Need to make them stand out more. I like Don's idea of the foam and epoxy. You could get a nice shape with foam. The epoxy will prevent any leaking or deterioration.I agree with Ed A., they need to be there. But I don't think you can pour epoxy down in there unless you make a dam first. If you are going to make a dam you might as well just fill that area. Use the foam idea or whittle some wood like I did. Enough West System to fill that area is going to be expensive. It really needs to be 3" thick instead of 2" like I made it. Then when you hammer it back to the stern end it will be sure to catch the screws.

 

[CHET]

I GOT FLAPPERS TOO

during my last haul i took them off and painted behind them to cut down on the growth then put them back on

 

[Ed Schenck]

Removing "flappers".

I neglected to mention removing them to paint. Like Chet I always remove them when applying bottom paint. The anti-fouling does nothing to stop the zebra mussels back there however. They do not bother the fiberglass, just the rubber flappers. And only on the inside.But putting them back on every year the holes started to get worn and I would go to bigger stainless screws. And more 3M 4200. That is when I decided to fill that void.

 

[Osprey17220]

Hull thickness?

OK , I think I am following this.It's a little hard to picture, not having a boat to look at....)I would think that the hull would be thicker that the screws would need to be long....I can't imagine that Hunter would just screw through the hull into the bilge....What were they thinking?Still boat shopping....Osprey

 

[Ed Schenck]

Hull "thinness", not . . .

thickness. The hull is suprisingly thin back there, maybe 3/16" or less. Yep, they put those screws through a hole right into the bilge.

 

[Ed Schenck]

Revised picture.

Here is a closeup from Jerry's photo. Note that the last 1.5 inches of the hull is recessed. This recess allows the flapper's leading edge to be flush with the hull.