Hull Shapes----Show us your girl's bottom

Vashon_Trawler · Jun 16, 2013

Thanks, ManyBoats! That is neat! You posted the commercial version of mine, which was set-up for salmon fishing--I haven't seen this one before. I believe Vashon Boat Works made two versions. Notice the wheel house is slightly larger on mine. My diesel is aft and in what would be the "fish hold" on the commercial version. I thought mine would look "cool" with outriggers and a cross-tee but wifey said no!

I guess I really have a "troller". Am I still allowed on this forum?

Moonstruck · Jun 16, 2013

Vashon_Trawler said:
Those are some beautiful bottoms! Here is the end of my modest little pocket trawler... full displacement... 16x10 prop on 1.25" shaft. She'll cruise comfortably at 6 knots, which is about hull speed. Draft is around 3' 3".

van der Kaay 4.10 2013 (4) | Flickr - Photo Sharing!

Dirk Peters · Jun 28, 2013

87 tonnes of Bottom

My dinghy makes more wake at 10 Kts.

Nomad Willy · Jun 28, 2013

Dirk thanks for the really excellent example of what a good full displacement hull should look like. This is the end of the boat that tells what a boat can do. This particular old girl is no doubt heavy.

A canoe is a FD hull too. It will exceed hull speed but T>B>Mclint... won't.

FlyWright · Jun 28, 2013

Great shot, Dirk!

Nimble1 · Jun 29, 2013

Nimble Nomad

Best shot I have of the boats hull. It has a keel that runs about 3/4 of the hull. The builder actually added about 3 additional feet after it was built (hull#1) as it did not track well. She is basically a flat bottom sharpie style hull designed by Ted Brewer of sailboat fame.

brian eiland · Jul 25, 2013

Firefly's bottom

reference photos here
http://www.trawlerforum.com/forums/showpost.php?p=161559&postcount=134

manyboats said:
Scott,
I wouldn't call her "sailboatish" at all. Full displacement to be sure and probably the most efficient boat here on the forum. Firefly has a very slippery hull. She's a looker too.

Island Eagle w her much higher displacement and high buttock line angle (angle of the rake of the stern) is also very much a full displacement craft. Neither boat is more or less a full disp craft but Firefly is considerably more efficient.

Do you think she could have an even harder chine from her midpoint length to her stern?....along with a 'flat plate' low-deadrise V section to her central keel? I ask in consideration of building the hull for one of these with steel panels.

Then maybe some bilge keels of some sort to resist some rolling ?

brian eiland · Jul 28, 2013

IslandEagle said:
Here are some pictures of Island Eagle up on the ways. The last one shows Jesse of Nanaimo Shipyards getting ready to cast in place the prop zinc, and it gives you a good idea of the scale.

What size vessel is this?

Is the hull shape similar to any other DeFevers?

Blue Heron · Jul 28, 2013

So would people agree that a keel that runs all the way to the stern is a full keel?

Nomad Willy · Jul 28, 2013

"would people agree" indicates that you think it is and I agree. It's more or less a full keel as I see it. A bit less in that the keel isn't 100% full. It's cut off at an angle. There keels that are much "fuller" than yours (mine for example) but if you were having lunch w a group of pleasure trawler skippers you would claim to have a full keel.

It's a bit like the FD, SD and planing hull types. There is no definitive point where one can say this hull is FD or Planing. It's all a grey zone. Attempts have been made to nail the issue down but in order to make a relatively positive definition one must understand such things as the quarter beam buttock line and other things common to discussions on Boat Design.net but not usually on a forum like TF.

But no to your question re "all the way to the stern". One quarter of the way aft of your stem ther'e is probably little or no keel. And on my Willard the keel dosn't extend all the way to the absolute stern of the hull. But ther'e is a lot of keel fwd as well as aft. However most all trawler yachts have a keel that that tapers down to next to nothing in the fwd end so it's really not full. But if a keel starts (aft) just ahead of the prop and extends below the prop and carries most or about 3/4 of it's draft (depth) fwd to very close to the stem it is beyond a doubt a full keel.

Codger2 · Jul 28, 2013

manyboats said:
There keels that are much "fuller" than yours (mine for example) but if you were having lunch w a group of pleasure trawler skippers you would claim to have a full keel.

Eric: I don't consider my keel to be "full." I could be wrong but I have seen single screw boats (as you said) with a much fuller (complete) keel.

IslandEagle · Jul 28, 2013

brian eiland said:
What size vessel is this?

Is the hull shape similar to any other DeFevers?

She's 60 feet long. The hull shape is not similar to other DeFevers, for the simple reason that the hull was not designed by Art DeFever. This boat was originally built as a "Baby Clipper" tuna fishing boat, by the Boyce Brother in San Diego. The original owner was in the market for a big, tough passagemaker, and bought the boat which at that point was close to being launched.

He had Art design the cabin and superstructure, converting the aft fish hold to a massive aft cabin.

So, I sort of have the best of both worlds, a boat that was built to be a fishboat but then never fished

Here are some pictures of the boat during construction: The Building of Island Eagle - Island Eagle

Attached are the hull lines.

And if you want to see what tuna clippers were for, and why the stern is shaped the way it was, watch this incredible video: Tuna Fishing and Canning: "The Fighting Tuna" Del Monte - YouTube

Scott Welch
Island Eagle

Blue Heron · Jul 28, 2013

manyboats said:
"would people agree" indicates that you think it is and I agree. It's more or less a full keel as I see it. A bit less in that the keel isn't 100% full. It's cut off at an angle. There keels that are much "fuller" than yours (mine for example) but if you were having lunch w a group of pleasure trawler skippers you would claim to have a full keel.

It's a bit like the FD, SD and planing hull types. There is no definitive point where one can say this hull is FD or Planing. It's all a grey zone. Attempts have been made to nail the issue down but in order to make a relatively positive definition one must understand such things as the quarter beam buttock line and other things common to discussions on Boat Design.net but not usually on a forum like TF.

But no to your question re "all the way to the stern". One quarter of the way aft of your stem ther'e is probably little or no keel. And on my Willard the keel dosn't extend all the way to the absolute stern of the hull. But ther'e is a lot of keel fwd as well as aft. However most all trawler yachts have a keel that that tapers down to next to nothing in the fwd end so it's really not full. But if a keel starts (aft) just ahead of the prop and extends below the prop and carries most or about 3/4 of it's draft (depth) fwd to very close to the stem it is beyond a doubt a full keel.

Thanks. I didn't open my statement "would people agree" to mean I am in agreement. I was asking if the consensus is that the keel I have is a full keel. I was not exactly sure before.

By your definition, I can say it is. It doesn't extend from the farthest point aft, however the props and running gear are above the deepest draft of the keel and it does extend for the 85% of the bottom of the hull.

If I were in such a lunch with a group of trawlers skippers, I would now make the claim that I have a full keel. Thanks

brian eiland · Jul 28, 2013

IslandEagle said:
....So, I sort of have the best of both worlds, a boat that was built to be a fishboat but then never fished

Here are some pictures of the boat during construction: The Building of Island Eagle - Island Eagle

Scott Welch
Island Eagle

Thanks Scott, I really enjoyed your website. Very informative.

It did appear as though a number of the links within the texts were no longer functioning, ...perhaps because of hosting?

N4712 · Jul 28, 2013

Here's some pics during our haul out.

markpierce · Jul 28, 2013

The Coot's keel starts about at the front of the pilothouse and "grows" as it get towards the stern, and extending to the bottom of the rudder with a gap for the propeller. That's about as full a keel for a motorboat as I've seen.

Giggitoni · Jul 28, 2013

SCOTTEDAVIS · Jul 29, 2013

Nomad Willy · Jul 29, 2013

Scotty I still think you've got the most efficient boat on the forum.

Nomad Willy · Jul 29, 2013

SeaHorse II said:
Eric: I don't consider my keel to be "full." I could be wrong but I have seen single screw boats (as you said) with a much fuller (complete) keel.

Walt I think most trawlers are as yours is but I don't see why designers didn't carry the keels full depth most all the way fwd. Windage is almost always fwd of center and w a full keel all the way fwd as my Willard basically has it STILL falls away to leeward more fwd than aft. From that one could conclude that w a keel like yours and a high bow like yours the bow swinging down wind must be a fairly serious thing in cross winds but I don't hear much about it.

I don't see why the keels weren't carried much further fwd on slower boats like trawlers. If your going to hit the mud, rock or sand bar it may even be an advantage to get stuck on the fwd end. Only other possible downside I see is a bit more wetted surface but nobody even talks about that re bilge keels. Wouldn't be that hard of an add-on either. I wonder how a boat (trawler) would handle w a keel like your's turned around. Deep end fwd shrinking as you go aft to next to nothing near the prop. Would need struts and the shaft would be exposed ... don't see either as an issue.

Yea Yea I know ... Far out.

markpierce · Jul 29, 2013

Extending the keel all the way forward would reduce maneuverability.

Tad Roberts · Jul 29, 2013

manyboats said:
Yea Yea I know ... Far out.

Not that far....google AXE bow.......

LarryM · Jul 29, 2013

markpierce said:
Extending the keel all the way forward would reduce maneuverability.

Mark,

The Willard/Fales underwater profile and full length keel does not impair maneuverability in the least. I can back and fill Boomarang easily in a boat length, and at speed, a turn to the favored side happens very quickly. I suspect Eric could confirm this as well. I really think it is very dependent upon the hull form.

psneeld · Jul 29, 2013

Did this google image search of "trawler rudder"...most of the first pictures had the keel extending aft to a shoe that attached to the bottom of the rudder.

Judge for yourself "what is more common"

albin 40 - Google Search

brian eiland · Jul 29, 2013

manyboats said:
Scotty I still think you've got the most efficient boat on the forum.

Its certainly one of my favorites for a coastwise trawler.

I'm thinking of a few modifications ?
1) Steel plate hull from deck level (bottom of that dark stripe on Firefly)down with a little harder chine shape like Island Eagle.
2) Island Eagle shape would be easier to fabricate in flat panel steel, and it would result in a little more displacement volume for the vessel.
3) That extra displacement shape would allow for a 'reasonably' thicker steel plate with less smaller-pieces of internal framing. This extra weight of the hull would be down low contributing to less rolling moments.
4) Then we save weight on the top. The deck and all superstructure from the bottom of that dark stripe on Firefly all way up including the roof of the saloon and pilot house would be built from resin infused polypropylene honeycomb panels. I believe you could save as much as 40% off the current weight of that structure that exist. Wow, what that might do for her rolling motions.

markpierce · Jul 29, 2013

psneeld said:
Did this google image search of "trawler rudder"...most of the first pictures had the keel extending aft to a shoe that attached to the bottom of the rudder.

Judge for yourself "what is more common"

albin 40 - Google Search

That's odd. The google images contain three photos of my Coot, but they are all interior shots.

psneeld · Jul 29, 2013

markpierce said:
That's odd. The google images contain three photos of my Coot, but they are all interior shots.

saw one of her bottom someplace on the net...don't worry

IslandEagle · Jul 29, 2013

brian eiland said:
1) Steel plate hull from deck level (bottom of that dark stripe on Firefly)down with a little harder chine shape like Island Eagle.
2) Island Eagle shape would be easier to fabricate in flat panel steel, and it would result in a little more displacement volume for the vessel.
3) That extra displacement shape would allow for a 'reasonably' thicker steel plate with less smaller-pieces of internal framing. This extra weight of the hull would be down low contributing to less rolling moments.
4) Then we save weight on the top. The deck and all superstructure from the bottom of that dark stripe on Firefly all way up including the roof of the saloon and pilot house would be built from resin infused polypropylene honeycomb panels. I believe you could save as much as 40% off the current weight of that structure that exist. Wow, what that might do for her rolling motions.

Just for interest, here is a steel sister ship to Island Eagle, built for Harry See of See's Candy.

http://www.yachtworld.com/boats/196...2476696/Emeryville/United-States#.Ufc2ycu9KK0

Scott Welch
Island Eagle

CPseudonym · Jul 30, 2013

brian eiland said:
Steel plate hull from deck level

<snip>

Then we save weight on the top. The deck and all superstructure from the bottom of that dark stripe on Firefly all way up including the roof of the saloon and pilot house would be built from resin infused polypropylene honeycomb panels.

Do you have an example of how the joint is made at the material transition zone?

Has this construction method been used on a vessel of similar size?

Nomad Willy · Jul 30, 2013

Mark on that link psneeld put up there's 4 FOUR images of your Coot.
How did that happen?
Yes ... frequently a batch of pics meant to show a boat fail to show the most interesting part.

TAD I've looked at lots of Axe bows on BoatDesign and wonder about their directional stability but many large boats (even ships) have the full blown axe bow feature. I would think turning on the face of a big wave would give most any helmsman a new white knuckle experience. But maby a big rudder is all that's needed.

Larry M,
Yes I can confirm that w my 45 degree swinging rudder Willy turns amazingly sharp. I can easily imagine why someone would think not though. The Willard/Fales hull does carry the keel all the way fwd but it's not much more than half it's former size when it reaches the bow but still very much a full keel. I suspect that the reason for that is that Rod Swift who designed them usually designed sailboats. I've not seen his other work.
With the low cabin your Boomerang sure looks longer than Willy.

I think the term "full keel" has more meaning re sailboats.

Hull Shapes----Show us your girl's bottom

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