Shoal Draft v. Full Depth Keel

[El Pinguino]

No... refer back to OP #1

'I have been looking at new boats and am wondering what the advantages/disadvantages are with shoal draft keels. Beyond the obvious draft difference what are the pros cons? '

The Island Packets, the Ovnis and the ones you have decided to ramble on about are all contemporary designs and are all in production.
Please try and stay focused rather than wandering off with your very own private agenda ... whatever that may be.....

[Polux]

Originally Posted by El Pinguino

No... refer back to OP #1

'I have been looking at new boats and am wondering what the advantages/disadvantages are with shoal draft keels. Beyond the obvious draft difference what are the pros cons? '

The Island Packets, the Ovnis and the ones you have decided to ramble on about are all contemporary designs and are all in production.
Please try and stay focused rather than wandering off with your very own private agenda ... whatever that may be.....

Being in production is not the same to be a contemporary design, a thing the IP is not. Here you have the IP 38 designed 35 years ago:

and here you have the IP 370:

As you can see the IP 370, the one that is on their catalog now, is basically a 35 old design, not a contemporary one, the biggest difference seems that know the design is a colored one. The old 38 looks more elegant to me.

With the other models on the line is practically the same except with the Bluejacket but that one is not an Island Packet.

What was you sayng about me rambling about? or private agenda?...that is just odd

[El Pinguino]

I think we need to define 'contemporary'... the older you get the broader the time scale. Maybe a discusion on 'contemporary seaworthiness' is called for.

OK moving right along... is the Hallberg-Rassy 48 Mk II 'contemporary'? HR says its 'new'....
The keel looks a lot like my 30yo contemporary one.... Hallberg-Rassy - Yachts - Center Cockpit Boats

[El Pinguino]

How about this http://www.amel.fr/upload/amel_55/55anglais.pdf
Looks pretty contemporary to me...

And back to the OP..... you can't do this with a high aspect ratio keel... its a bit more important to me than the ability to point a few degrees higher...

[Randyonr3]

Originally Posted by Boatyarddog

High aspect refers to the shape of a foil as it cuts through its fluid. A deep keel with a short chord where it attaches to the boat, and a tall mainsail with a short boom would be high aspects. Gliders have long, narrow wings: high aspect. A shallower keel with a long keel/hull joint, a mainsail on a short mast with a long boom would be low aspect. Supersonic fighter planes have short, wide wings: low aspect. A solent jib is considered high aspect. A genoa would be low aspect. The term is relative. It comes from "aspect ratio", which compares the leading edge length of the foil to its chord length. CCA rigs were designed typically with low aspect mainsails. IOR boats with their short booms generally have high aspect mains. High aspect foils develop more lift for their size than low aspect foils. This is one of the reasons deep keel boats do better to windward than full keel boats. There are points of diminishing returns however. If the keel's too deep, you start to hit things with it. If the mast's too tall, you heel too much, and the weight you have to carry to compensate for it slows the boat down. It's all a balancing act.

Keel design and sail, mast combinations, will vary results with regards to windward performance.
Full keels track better because of the length of the keel under the boat.
Ask the guy with the Fuji Ketch, the hull on his boat is the same as the Mariner ketch.
I don't know what 40 your referring to as "your last boat".
There are many different keel designs out there. Why? Because they allow the boat to do certain things better than other designs.
Otherwise they would all have the same keel design.
Nuff said.

And sometimes you just gota laugh......... I didnt say "40 foot boat as my last boat" read it again and do some research befor you spout off..

[Polux]

Originally Posted by El Pinguino

How about this http://www.amel.fr/upload/amel_55/55anglais.pdf
Looks pretty contemporary to me...


And back to the OP..... you can't do this with a high aspect ratio keel... its a bit more important to me than the ability to point a few degrees higher...

Sure, the Amel 55 is a contemporary ketch even if conservatively designed and it has a modern hull and a reasonably contemporary designed keel, a bulbed one, even if its design in what regards efficiency is limited by the need to contain that odd engine transmission system, with the propeller on the keel. That transmission system is probably the item on the boat that Amel owners complain more about.

This is the hull and keel of the Amel 55, the one that refers to the PDF you posted:

What is odd in your post is that the photo you posted to refer that "it looks contemporary to me" refers not to an Amel 55 but to an older boat and not even an Amel,

a boat with an old designed keel, a modified non bulbed fin, that is not used by Amel since the Amel Mango and Sharki, models from 1979 and 1980.

That's why Amel are great boats: They are relatively conservative yachts but they have been modifying continually their hulls, keels and rudders to maintain them as contemporary boats, contrary to other conservative brands, for instance, Island Packet or Cabo Rico.

[Scout 30]

This thread is full of generalizations. Clearly there are benefits to deep draft designs. If there weren't all boats would be shoal draft designs. Every boat design is a trade-off. About the only generalization you can make about deep draft boats vs shoal draft boats is that deep draft boats need more water to sail in than shoal draft boats & even that will probably get an argument. You just need to decide what trade-offs you are willing to live with.

[Polux]

Originally Posted by El Pinguino

I think we need to define 'contemporary'... the older you get the broader the time scale. Maybe a discusion on 'contemporary seaworthiness' is called for.

OK moving right along... is the Hallberg-Rassy 48 Mk II 'contemporary'? HR says its 'new'....
The keel looks a lot like my 30yo contemporary one.... Hallberg-Rassy - Yachts - Center Cockpit Boats

Do you mean that old Halberg Rassy are more seaworthy than new ones

Halberg Rassy have also being continuously improve their hulls keels and rudders. I agree that they are a conservative brand and that means that in terms of contemporary design they are slower to improve their designs than less conservative brads. That has to do with the needs to maintain a conservative clientele happy, not scaring them with anything really contemporary.

But 30 years ago what they were proposing in therms of keels was this (HR 49 from 1982)


Regarding the 48MKII, even if not a 30 year old designed keel I agree that it is not a contemporary keel (not a bulbed one), but the HR48 is not also a contemporary design but a more than a decade old one. As you should have seen it is a MKII, that means that is a partially new boat using the hull of a previous boat.

Regarding being contemporary in design I have already explained that it has nothing to do with the boat having a new interior or a slightly different hull but regarding the hull keel and rudder, the underbody, to be a contemporary design or not.

As you can see on the new boats (that don't use older hulls) Halberg Rassy have already contemporary bulbed fin keels and rudders (the 412 and 64)

[Polux]

Originally Posted by Scout 30

This thread is full of generalizations. Clearly there are benefits to deep draft designs. If there weren't all boats would be shoal draft designs. Every boat design is a trade-off. About the only generalization you can make about deep draft boats vs shoal draft boats is that deep draft boats need more water to sail in than shoal draft boats & even that will probably get an argument. You just need to decide what trade-offs you are willing to live with.

There are some designs, even mass produced main market boats that are offering variable draft designs that can offer the best of two worlds, namely Jeanneau on the 349 and 379.

This keel offers a very similar performance compared with the deep draft keel, some even say, a better performance.

The 349 that won the Cruising World magazine award for best pocket cruiser. They said about it:

"Given such competition, it would clearly take an exceptional boat to rise to the top. That’s what the judges discovered when they boarded Jeanneau Sun Odyssey 349. After a thorough inspection, they named it not only the year’s top Pocket Cruiser, but also 2015’s Import Boat of the Year. With over 100 already built and sold, the marketplace has already spoken. There’s just tons to like about this “little big boat.”
First off was the cost. The base price for the 349 is $125 thousand, though the model we tested — tricked out for racing with a square-topped mainsail and other competitive goodies, along with reverse-cycle air conditioning, a microwave and other liveaboard features — topped off closer to $165 thousand. But that’s one of the attributes of the boat; even in a 34-footer, there’s room both to customize the yacht and to cut costs on items you don’t find essential. It’s also versatile, as the owner of our test model — a dedicated Chesapeake racer who also wants to take his young family on fun Bay adventures — noticeably typified.
“It’s the lowest-priced boat in this class and represents exceptionally good value,” said Sherman. “It could be a terrific entry-level cruiser for a young couple or someone just starting out, but it could also be a fine option for someone scaling back from a larger yacht who still wants to go cruising in a good sailboat.”
“It’s a Marc Lombard design,” said Murphy, “and you can see in the whole Jeanneau range that they are really paying attention to how the boats sail. I think we see that more clearly in the Jeanneau line than we do with other builders with offerings in this size range.”
“The cockpit worked for me,” said Mark Schrader, “and so did the twin wheels and twin rudders. It’s typical Jeanneau grid construction, which they have dialed in very well. I do think they’re giving themselves short shrift when they say it’s an ‘entry-level’ boat. I’m not an entry-level sailor and I really like it.”
Sherman summed up the judge’s collective opinion concisely: “It has come in at such an exceptional price for what you get that it’s really the best value in the entire contest.” The formula, then, is simple: Marry value with quality and the result is a winner."

2015 Pocket Cruisers: Compact Cruisers for Quick Getaways | Cruising World

[El Pinguino]

Originally Posted by Polux

What is odd in your post is that the photo you posted to refer that "it looks contemporary to me" refers not to an Amel 55 but to an older boat and not even an Amel,

Apologies, there must have been a punctuation and spacing issue in my post . 'Looks contemporary to me' refered to the amel link above the statement.

The photo of my boat was covered by the statement below it.

This goes back to the OPs question - when you go for 4 years or more with no access to 'traditional' haul out facilities it is handy to have a keel you can dry out on.

[Polux]

Originally Posted by El Pinguino

...
This goes back to the OPs question - when you go for 4 years or more with no access to 'traditional' haul out facilities it is handy to have a keel you can dry out on.

Yes I agree but how the hell is he going to sail for 4 years without having haul out facilities? In what regards small yachts they are in almost all small harbors, including certainly the ones you have posted.

But I agree also that there are many situations where a boat that can dry up will become handy but in that case the best option it will not be a big modified fin keel, as you have posted, but a bilge keel (twin keel), an integral centerboarder (OVNI, Allures, Boreal or Garcia), a Swing keel with two rudders (Jeanneau, Southerly, Pogo) or almost all cats and trimarans.

I agree that after all those options a modified fin keel or a full keel is the best option even if it will need a quay or pontoon to hold on to, but those options have bigger implications on loss of sailboat performances (more the full keel than the modified fin one).

Regarding letting the boat go on its side, it is not recommendable for many reasons but in sand and inside a port on settled conditions you can do that with any boat.

[Jim Cate]

I'm not sure what you mean by a "modified fin keel", but good balance is possible with a fairly short length fin. Attached see a photo of Insatiable II, balancing upon her keel on a very small slipway trolley... note that there are no braces required, she just stands there all on her own! And most would say that she has a reasonably modern hull shape, just not a bulbed and high aspect strut type keel.

The PO and builder careened her on a beach in Alaska some years ago, too. Braver than I am...


Jim

[Randyonr3]

Originally Posted by Polux

I agree that after all those options a modified fin keel or a full keel is the best option even if it will need a quay or pontoon to hold on to, but those options have bigger implications on loss of sailboat performances (more the full keel than the modified fin one).
.

I'm not sure how much of a loss a full-fin would be over a short fin with a bulb..
Remember, we're cruisers here.. and ours is alot like Jim's as the stands are there just to keep her from falling over..

[Polux]

Originally Posted by Jim Cate

I'm not sure what you mean by a "modified fin keel", but good balance is possible with a fairly short length fin. Attached see a photo of Insatiable II, balancing upon her keel on a very small slipway trolley... note that there are no braces required, she just stands there all on her own! And most would say that she has a reasonably modern hull shape, just not a bulbed and high aspect strut type keel.

The PO and builder careened her on a beach in Alaska some years ago, too. Braver than I am...


Jim

I call a modified fin keel what they call a modified fin keel:
Gozzard Yachts Brokerage - Gozzard Yachts Brokerage.


Being bulbed has nothing to do with that (that is the same thing being bulbed or not), being just a very narrow racing foil with a torpedo bulb can have more problems. Most boats with a fin keel can stand on the keel for some time even if it is a lot more safe to take also hull support to prevent any hull deformation on the long run.

But one thing is to put the boat carefully over its keel, other is let him dry out against a pontoon over a somewhat irregular bottom and in what regards that a modified fin keel or a full keel give a lot more confidence and support.

[El Pinguino]

Originally Posted by Polux

Yes I agree but how the hell is he going to sail for 4 years without having haul out facilities? ....

Same way I did/do I guess.

Jim, thats not a high aspect ratio fin on your boat..... this is.....

According to Polux... all boats are designed with ones like this these days.....