I haven't followed yachts closely enough in the past couple of decades
to comment on individual designs. However,

I can't remember ever seeing anything by Bob Perry that I didn't like.
Brewer/Wallstrom have designed some nice boats but I know I had the
"Why did they do that?" reaction much more often back when I looked at
every yacht design I came across.

Most of my career has been spent on metal vessels. If I were going
around the world, I'd want to go in a steel or aluminum boat. I'd
favor aluminum because of a more reliable compass and because you can
patch it with a hand drill and sheet metal screws. Aluminum tends to
bend flat and intact where steel fractures even though it is stronger
in the stiffness sense.

I once saw an aluminum yacht that went ashore on Nomans Land Island.
The keel was torn off and one side was pounded in about five feet for
three quarters of the length of the vessel. There were only about
three six inch cracks that would have let water in. If she had been
worth saving, she could have been made watertight and floated off with
a roll of duct tape. A steel boat would have been in pieces all over
the beach.

The key thing I would look for is a full length skeg along the leading
edge of the rudder all the way to the bottom. The directional
stability comes from that fixed foil. Turning the rudder makes it a
lifting surface in the direction you want to move the stern. A lot of
the turning force then is created by something fixed to the hull
instead of on a hinge where you have to resist it with your hands.

The typical semi skeg with a bit of balance forward (as on the
Endeavors) is a silly arrangement usually. There isn't enough balance
on 90% of the rudders you see to effect the helm forces, the
directional stability is reduced, and a line catcher created. The
only rational for this kind of rudder is to look techie like an
airplane.

Our boat had glass added to the forward part of the rudder to increase
the balance to an amount that will actually do something. 15 to 20
percent should be ahead of the hinge line. Some winter, before that
trip around Newfoundland and up to Labrador, I'd like to cut it back
and extend the skeg all the way down though. It's an easy conversion
on most boats.

For directional stability, you want lots of leading edge back there.
I think my beef with a lot of Brewer/Wallstrom boats was that the
cutout ahead of the rudder is often kind of a token so that there is
very little leading edge.

--

Roger Long



"rhys" wrote in message
...
On Thu, 14 Apr 2005 16:39:41 GMT, "Roger Long"
wrote:

Personally, I like cutaway forefoot, skeg hung, semi-full
keelers.
Best of all worlds if designed right.

This boat designer agrees with you which is exactly why we bought
the
Endeavour 32.

OK, Mr. Designer...I am glad I am on the right track...I seem to be
a
lone voice in the wilderness advocating a number of older Ted
Brewer/Bob Wallstrom/Robert Perry designs G.

On the used boat market, what models would you recommend "like this"
but in the 38-45 foot range? I also favour steel if well constructed
and coated originally, which is admittedly a big "if".

Your opinion would be most appreciated.

R.

Here is a picture of how the rudder was enlarged on our boat with the
original line shown:

http://home.maine.rr.com/rlma/Rudder.jpg

The balance is still pretty minimal but you can see that there was
effectively none before.

The way I would modify it is shown in red.

--

Roger Long

In article ,
Stephen Trapani wrote:

Hull speed is the absolute maximum that boat can travel through water.
All your examples have the water moving forward also so the boat is not
exceeding hull speed through the water.

I thought I mentioned this before. Hope I'm not repeating myself.

Hull speed is a suggestion for our boat, not the law. Though our
theoretical hull speed is 6.65 knots, we regularly exceed that with
aplomb, close hauled, close reach, broad reach, whatever point of sail.
Spent a wonderful afternoon with 6 other sailors last season. As long as
I was on the tiller, pushing her to where she likes to be, we were well
above the theoretical hull speed. As we pinched to get back into the
harbor, she insisted on doing over 7 knots directly into the wind (okay,
about 15 degrees off). That last was our lovely lady showing off, of
course, as what we did was clearly impossible.

1.34 was derived from observing boats about a century ago. Depending on
the hull, that constant can be quite a bit different. As I recall, some
multi-hull boats' K is in the 2 or 3 range. Xan's fat ass and sharp
transom keeps her driving towards a 1.7 or so constant.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

On Sat, 16 Apr 2005 09:32:25 GMT, "Roger Long"
wrote:

Comments below.

Most of my career has been spent on metal vessels. If I were going
around the world, I'd want to go in a steel or aluminum boat. I'd
favor aluminum because of a more reliable compass and because you can
patch it with a hand drill and sheet metal screws. Aluminum tends to
bend flat and intact where steel fractures even though it is stronger
in the stiffness sense.

Interesting. I work with aluminum on the mast and I've fabbed up 1/4
in. backing plates for most of the deck gear, so I know simple hand
tools will suffice, but usually the knock AGAINST aluminum is that it
requires special welding gear and skills. I didn't think of it in
terms of making a through bolted patch and running a bead of sealant
around...but why not as a "get you home" metallic fothering?

I once saw an aluminum yacht that went ashore on Nomans Land Island.
The keel was torn off and one side was pounded in about five feet for
three quarters of the length of the vessel. There were only about
three six inch cracks that would have let water in. If she had been
worth saving, she could have been made watertight and floated off with
a roll of duct tape. A steel boat would have been in pieces all over
the beach.

I would think it would be worth saving for the aluminum alone...isn't
"marine" aluminum a fairly expensive alloy?

The key thing I would look for is a full length skeg along the leading
edge of the rudder all the way to the bottom. The directional
stability comes from that fixed foil. Turning the rudder makes it a
lifting surface in the direction you want to move the stern. A lot of
the turning force then is created by something fixed to the hull
instead of on a hinge where you have to resist it with your hands.

I'm a big fan of skegs for safety and directional reasons. If you
ground by the stern with a spade rudder, usually it's game over. A
skeg can help...maybe...to save it.


The typical semi skeg with a bit of balance forward (as on the
Endeavors) is a silly arrangement usually. There isn't enough balance
on 90% of the rudders you see to effect the helm forces, the
directional stability is reduced, and a line catcher created. The
only rational for this kind of rudder is to look techie like an
airplane.

So you're no fan of the "Brewer Bite"?

snip
For directional stability, you want lots of leading edge back there.
I think my beef with a lot of Brewer/Wallstrom boats was that the
cutout ahead of the rudder is often kind of a token so that there is
very little leading edge.

I am not sure of the logic either, except that it makes otherwise
traditional boats more "modern" looking on the undersides.

R.

On Sat, 16 Apr 2005 09:56:17 GMT, "Roger Long"
wrote:

Here is a picture of how the rudder was enlarged on our boat with the
original line shown:

http://home.maine.rr.com/rlma/Rudder.jpg

The balance is still pretty minimal but you can see that there was
effectively none before.

The way I would modify it is shown in red.

Good picture! Thanks for your thoughts.

R.

I'm a big fan of skegs for safety and directional reasons. If you
ground by the stern with a spade rudder, usually it's game over. A
skeg can help...maybe...to save it.


Just to clarify: That is a fixed skeg shown on my proposed
modification.

On spade rudders: On power boats, I favor spade rudders. If the
rudder has good clearance from the hull at the top, it will often
remain functional after a grounding. The shaft may bend and the boat
steer funny but it will still be steerable. With a bottom bearing, a
little bit of bending will usually bind the whole thing up so if is
useless. In a glass boat, it will be hard to make the skeg stiff
enough to support the rudder. The whole thing can flex enough that
the shaft will bend and the skeg will then bind the rudder. Even in
metal, the sailboat type skeg will be hard to make sufficiently stiff.

It doesn't take a lot of extra metal to make a rudder stock strong to
be self supporting. If I were designing a boat that was not a weight
critical racer, I would make the stock large enough to be a spade
rudder. The skeg would then be structurally separate with just a line
guard at the bottom. Grounding damage, which usually will bend the
stock aft, would then leave the boat steerable in most cases.

--

Roger Long

Stephen Trapani wrote:
Hull speed is the absolute maximum that boat can travel through water.

Not really. "Hull Speed" is sort of a convenient shorthand for
indicating where the graph of a vessel's speed vs power begins to get
inconveniently steep.


All your examples have the water moving forward also so the boat is not
exceeding hull speed through the water.

Even catamarans? How about planing types?

DSK

wrote:
One of these days I'd like to look into the derivation of hull speed.

Check out the work of William Froude.

Can you suggest a very basic explanation (a source thereof). I'm just
curious as to when it applies. Like:

Does it apply to non-rigid hulls (hulls that might flex in the middle)
Does it apply to totally submerged objects?
Does it apply to towed objects, like dinghies?

Yes, yes, & yes.
Usually making hulls non-rigid makes them slower for given power. There
are some interesting studies of marine mammals that can swim faster than
science suggests they should, and apparently they can change their shape
to promote laminar flow and possibly reduce wave pressure areas.

For totally submerged objects, the rules are a bit different and they
don't have the same limits as displacement-supported objects on the surface.


What happens when an object exceeds hull speed?

That depends a lot of the hull & the conditions. Some "objects" will
plane, ie will transition from being supported by displacement to being
supported by the dynamic lift of water flowing under the hull. In other
cases, the cross section density is high enough that wave resistance is
less (ie very narrow hulls).


Is there any way to "fool the water" into acting as if the boat is
longer than it is?


Sure, that's what bow bulbs are all about.

Fresh Breezes- Doug King

In article ,
DSK wrote:

Usually making hulls non-rigid makes them slower for given power.

One notable exception: a PortaBote, but that's not practical for most
hulls. The hull deforms unbelievably, which is disconcerting.

But, in general, it's true.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

On Wed, 20 Apr 2005 05:25:11 GMT, Jere Lull wrote:

In article ,
DSK wrote:

Usually making hulls non-rigid makes them slower for given power.

One notable exception: a PortaBote, but that's not practical for most
hulls. The hull deforms unbelievably, which is disconcerting.

It is hard for me to believe that is an exceoption.

It would be notable if so. Indeed, it would be a miracle.



Rodney Myrvaagnes NYC J36 Gjo/a

"Religious wisdom is to wisdom as military music is to music."