E30+ knotmeter location?

[eknebel]

I am thinking of relocating my knotmeter to the centerline in the vee berth compartment just forward of the waste holding tank. Is this where yours is? How does it perform? Other locations?
My knotmeter is currently located under the port settee, just aft of the mast. I have 1 to 2 knot differences close hauled( not on gps, plus I hope I could tell). I am confident this difference is caused changes in flow across the keel on opposing tacks, especially since I have the shoal draft version. I even replaced the knotmeter, with no real change.

 

[supersailor]

The knotmeter is best located ahead of the keel. From the keel aft, the disturbed water from the keel interferes with the flow over the paddlewheel. Mine is located in the storage area at the aft end of the foreberth just off the centerline. The hull is exceptionally thick on the centerline there.

 

[Loren Beach]

One small caveat about a "centerline" location (and may not be a concern where you sail) is that if you run over a log there might be a higher probability of breaking the impeller. having said that, the hardest hit we have taken was a deadhead that hit under the port side forward. It's kind of hard to 'plan' accidents!

 

[nquigley]

Or (?) - take this opportunity to have one less hole in your hull by abandoning the through-hull paddlewheel altogether and just rely on GPS for speed? They are not very accurate, and, depending on your sailing location, can become fouled with barnacles, etc, since they have no antifouling paint on them.
I filled in my paddlewheel hole several years ago when I was redoing the barrier coat.

 

[Frank Langer]

Or (?) - take this opportunity to have one less hole in your hull by abandoning the through-hull paddlewheel altogether and just rely on GPS for speed? They are not very accurate, and, depending on your sailing location, can become fouled with barnacles, etc, since they have no antifouling paint on them.
I filled in my paddlewheel hole several years ago when I was redoing the barrier coat.

Yes, I think one can manage well with just a gps, but a knotmetre comparison with gps gives useful information about the current, for those of us on the ocean. If my knotmetre indicates 6 knots and the gps speed over ground reads 4 knots, I know I'm battling a 2 knot current.
On our E30+ the knotmetre is located underneath the small bench locker at the forward end of the salon, just barely under the v berth. There is a plastic port opening at the bottom of that locker which provides access to the hull. The knotmetre is in there, where I can reach it and remove it to replace it with a dummy plug when I haul the boat so the travel lift sling doesn't break the impeller. It also allows periodic cleaning. With practice, I can now remove and replace it with only about a cup of water coming into the boat which is soaked up by a strategically placed towel.
That spot is on the starboard side of the hull, almost at centre line, about 4 to 5 feet at of the bow but ahead of the keel. It's perfect there.
Frank

 

[eknebel]

Thanks all for your input! I was so fixated on putting it on center because of my "flow" issue, that I lost sight that it was caused by the keel. Putting it off center would seem to lessen impact damage to the impeller, and much easier to fair.
Luckily we don't have many deadheads on the Chesapeake, although a few are crew from time to time. What we do suffer from is light winds, and any insight on currents can help with navigational choices. This project is for next winters haul out, but a hole is to be soberly contemplated. It was a more urgent issue, but I was lucky to find a $75 depthsounder transducer that got the old standard horizon working again(I am contemplating a depth/speed combo transducer).

 

[eknebel]

Frank, just to clarify where your access port is, I went down and took a picture. I think yours is where the red cuzie is, but maybe where the blue post-it note is? Of course, nothing is simple, and either one will require moving the waste holding tank to port. It is about time to replace the hoses again anyway, sigh.

 

[Frank Langer]

Frank, just to clarify where your access port is, I went down and took a picture. I think yours is where the red cuzie is, but maybe where the blue post-it note is? Of course, nothing is simple, and either one will require moving the waste holding tank to port. It is about time to replace the hoses again anyway, sigh.
View attachment 33071

Hi,
That is the correct locker, but because the liner angles down in there, my plastic port is about in line with the reflection in your picture, and my knotmetre is about at the edge of your cushion, so a bit to port of where you thought, but still just to the right of the centerline of the hull.
Frank

 

[eknebel]

So, to place the access port, move the red cuzie to be lined up with the reflection, and the knotmetre just to starboard of centerline? I am not sure if i can move the holding tank towards the bow enough to get space for the knotmetre between the aft inside edge of the locker and the tank. That is why I placed both markers to starboard, so the knotmetre would be to starboard of the tank. Is yours the original voluminous Ronco 13 gal tank(49L) or did it get moved elsewhere? Maybe things changed between #509 and #634.

 

[Frank Langer]

So, to place the access port, move the red cuzie to be lined up with the reflection, and the knotmetre just to starboard of centerline? I am not sure if i can move the holding tank towards the bow enough to get space for the knotmetre between the aft inside edge of the locker and the tank. That is why I placed both markers to starboard, so the knotmetre would be to starboard of the tank. Is yours the original voluminous Ronco 13 gal tank(49L) or did it get moved elsewhere? Maybe things changed between #509 and #634.

My holding tank is 15 gallons, on the port side. I also have an optional 19 gallon water tank forward of that locker and another locker at the foot of the v berth.
There should be lots of room for your knotmetre.
Frank

 

[eknebel]

Thanks, I am emboldened to now move the waste holding tank in preparation for the winter lay-up. I got time, since I can't go out on the water due to covid-19 restrictions.

 

[eknebel]

I did it! I installed my thru hull on the port side instead of starboard, since I didn’t have to move the holding tank, and no cutting a visible access port in the “v berth seat”(see above red cuzie). Just above the shelf for tank was as deep as I went(see green tape in 2nd exterior picture)
In the first interior picture , it is the square epoxy coated wood backing plate. I used a

Raymarine ST300 / P371 Thru-Hull Low-Profile Shorty Transducer

The shorty gave more clearance as it is removed upwards, angled towards the holding tank. I like the flap that reduces water coming in as you remove the impeller for storage/cleaning.
After 4 days in 15-25knot winds, I am happy to report the impeller only went airborne once or twice in 130 miles! When it did, I was thinking more of regaining control than a accurate speed thru water by by reading anyway!