Possible? Make a 36RH Shoal Draft?

[jmcpeak]

So I was thinking, dangerous I know...

If we end up moving to the Atlantic side of Florida (south) next year - my 6'6" draft of my 36RH is just not going to work.

Does anyone know if a shoal draft keel exits that would bolt directly up?

If not, could one be fabricated inexpensively?

I know this is an odd request, but I just wanted to know if it is practical or should I just throw out the idea...

Thanks!

 

[Frank Langer]

There is a company called "Mars" in Toronto, Ontario that does this kind of work. They will cut the bottom off the fin keel and add a keel bulb at the base, giving a shallower draft but still trying to maintain the right weight in the keel. They do the calculations to see what will work, and generally have a pretty good reputation. You may want to contact them.
Frank

 

[jmcpeak]

Found it:

MarsKeel - Technology
http://www.marskeel.com/

 

[Loren Beach]

Mars Metal narrative

http://www.ericsonyachts.org/infoexchange/showthread.php?t=6758&referrerid=28

Here you go, and there is yet another link within this earlier thread.

Loren

 

[Rocinante33]

Jason,

Arrgh..... don't do it!

I'm sure your 36 is not as tender as my 33, but it is the big brother to my boat. I cannot fathom (pun intended) removing any bit of my keel, in fact I think some more lead down there would benefit it with a bit more stiffness.

What would Ron Holland say?

 

[jmcpeak]

Keith,

I completely agree, but how do I handle the shallow waters of pretty much anywhere in FL?

Either I have to let her go and find another boat or make her shoal draft - they are the only two decisions I see...

 

[Loren Beach]

Remember that shortening the keel and making up for it with a split lead bulb is going to add more lead weight than was removed. This has to make up for the removal of ballast at the former bottom one foot of draft. Righting Moment should then be unchanged.

Mars Metal (if you use their services) should be able to do this very basic calculation with ease.
The only concern I would have is whether the keel bolt size and pattern and floors in that particular design have the designed-in reserve strength for the extra total keel weight. Knowing the extra-margin design strength that Ericson put into all of their other models, I would doubt that there would be any problem.

Perhaps too expensive, but maybe worth getting the original naval architect's professional opinion on this. http://www.ronhollanddesign.com/home.php
:nerd:

Just some thoughts on a cloudy morning...

Best,
Loren

ps: Jason, what draft can you live with, after the changeover? 5.5' ?

 

[jmcpeak]

Maybe Seth would venture a guess...

 

[Surfin Tiki]

Jason,
I have the 33RH and would never think that a shoal draft would be a do-able option . Have to agree with Keith on this one, although not sure how much stiffer the 36RH is. Perhaps the mast butt could be cut down to make up for the decressed stability?

Joel Graves

Ericson 33RH
Surfin' Tiki
VYC
Ventura, CA

 

[ted_reshetiloff]

Shortening the draft if done correctly WILL NOT REDUCE STABILITY. Mars does this all the time with great results. Loren has asked the most important question which is whether the floors can handle the higher loads. Mars can probably tell you that too but you may be able to get the answer from the designer.

 

[Surfin Tiki]

Found a thread where an E.Y.O. member considers purchasing, what he says is, an E36RH hull#2 with a wing keel and a 5' draft. If this is true, it has been done.

http://www.ericsonyachts.org/infoexchange/showthread.php?t=838

Joel Graves
Surfin' Tiki
E33RH
VYC
Ventura, CA

 

[Seth]

36 keels

As much as I would hate to do it, the Mars mod should be fine and keep stability the same. FYI (for those who wondered) the 36 is a lot stiffer than the 33..

I think some performance will be compromised-more in lighter air I would think, but it is a good all around performer, so if you are going to Florida, I can understand the position.

BTW- The Mars mod is MUCH better than a winged keel.

Good luck.

Sorry I have been off the grid, but I am back..

Cheers,
S

 

[Rocinante33]

Seth,

How much would the Mars bulb help with stiffening my 33?

Sorry to hijack the tread, but there is a bit of a relationship here.

 

[Seth]

shouldn't

The concept as I understand it is to achieve the same RM as with the original keel.

Of course you could add some weight to increase stability, but the idea is they remove some depth at the bottom and with the new shape achieve roughly the same RM with less draft.

Are looking to increase stability, or reduce draft?

If I had a 33, I would go with a new style deeper keel, but same weight. The new bulb style keels are much faster shape-wise, and by getting the weight lower you really increase RM. If you could live with another 10-12" of depth you could really perk the boat up-faster on all points of sail in all conditions and stiffer, too!

If you want to reduce draft and increase RM, go with the Mars mod, but add another 300 pounds or so. You will give up some light air speed for sure, but should do better in 12 kts up..

Make sense? If not, drop me a note..

S

 

[Rocinante33]

Seth,

Yes, everything makes sense. Still, it seems that the simple addition of a Mars bulb to the existing keel would add some RM and would certainly cost much less than a new keel. I realize that the best way would be to add the weight and lower it another 10-12 inches, thereby creating about 6'9" to 7' draft. That would probably be a dramatic addition to the RM. Maybe adding 300# at my current 5'11" depth would be a benefit, though, or maybe negligible.

I used to know someone who did this to his E38 and I think he was happy with it, though he left our marina & I lost contact with him. So I never got a solid report from him about the effect of the bulb addition.

Thanks for your comments, as always!

 

[rwthomas1]

FWIW, I have a Mars bulb on my E38. I've never sailed the boat without it but from what I have read my boat is a good bit stiffer than a standard shoal draft E38. I fly a full batten main and 130 genoa and don't reef until about 17kts true. I have heard most shoal draft E38's reef much sooner. The published draft is 4' 11" Mine is about 5' 4" or so. The only drawback I see to this is the boat has less weight carrying capacity? So cruising loadouts may be compromised? The way I use the boat, and intend on using the boat, it will not affect me at all. I you think your boat is too tender then this mod may be the solution for you.

RT

 

[Seth]

Here's the thing

If you think about it, it is not possible to ADD any RM by moving weight higher in the keel. The Mars mod for reducing draft involves adding weight to the new bulb to compensate. So I guess if you are willing to live with a heavier keel you can get the same stability (or more with more weight) with this mod-but there must be a weight penalty...

If someone knows otherwise, please correct me (Guy?).

Thus, to increase stability you have these options:
1). Same weight, but deeper keel
2). Add weight to the bottom of existing keel (which increases depth)
3). Mars mod which includes 10-15% more lead
4). Add weight in the bilge (not very efficient)

Mars mod alone without weight change will not increase RM.


Is this horse dead?

Cheers,
S

 

[jmcpeak]

Seth,

> BTW- The Mars mod is MUCH better than a winged keel

Why is a bulb better than a wing? Better upwind? Better light air? just curious.

Thanks for the reply about my 36RH. I hate to cut the keel off, but I'd hate more to have to sell her if we end up moving to FL. I really want to keep the boat but FL inter-coastal waters are SO shallow.

 

[Seth]

Keels

Q-Why is a bulb better than a wing? Better upwind? Better light air? just curious.

A-A bulb keel is a low drag hydrodynamic shape with the maximum amount of weight at the lowest possible depth.The bulb itself is also a low drag shape.

A wing keel, relatively, is a high drag shape which in theory would have reduced draft, and the idea is that the shape of the "wing" produces lift-enough so that it offsets the loss of depth. It never turned out this way-a good wing will approximate the stability of the deeper keel (at the same weights), but with a big drag increase. The bad ones accomplished neither.

If you take a conventional 80's style keel like yours and cut some off, but add a MARS bulb (which adds weight of course), you can keep the stability without a drag penalty, since it is a bulb shape, not a wing.

The best performance solution is to shape a new, thinner section deeper keel, and with all the weight you shave off in the process of reshaping, make a nice low drag bulb at the bottom. In fact since you are getting deeper, you might not have to use ALL the weight, and end up with a lower, lighter, and less draggy keel providing the same or better RM.

For Florida, the MARS is best-less draft, a little more weight, but same RM.

Got it?

S

 

[jmcpeak]

Got it?

Yes, and as always, thanks for taking the time to explain it so well.