Wide Keel #382 and up... vs earlier boats? Draft.

Zach · Post by **Zach** » Wed Jul 30, 2008 12:50 am

Hi guys...

I'm digitizing the line drawing of the triton to turn it into 3d...

I don't remember where I found the picture, or if its one of the ones I scanned in... (Brain fart!) but here it is:

http://img291.imageshack.us/img291/9838 ... 958ch4.jpg (Click to see... its big.)

Down there by the keel in the top sketch it says "Wide keel" on 382 on up. Well... I'm having a hard time telling if its the outer line or the inner line is the wider keel. Do the 382 on up have a deeper draft? 101 has external ballast, so thats what I'll draw first. (Has a note about displacement 110 vs 108... but with Triton's I'm learning to ask questions first before assuming anything that would be common sense. Grin!)

That drawing has the measurements/scale and what not. Theres one with a constellation rudder that lacks a lot of that... Which is a bit of a bummer, because the Pearson Ariel/Commander guys seem to like them, and Alberg didn't do any (?) later designs with the ear shaped rudder.

Anyhow... thanks!

Zach

Post by **Tim** » Wed Jul 30, 2008 6:14 am

Zach wrote: Do the 382 on up have a deeper draft?

To the extent of my generally anecdotal knowledge, the keels on the boats with internal ballast (#382 and up, by all accounts) are wider and a bit deeper than the earlier boats with external ballast.

The wider keels are most noticeable at the after end, since the internally-ballasted boats molded the keel in a single piece integral with the hull mold, versus the external ballast boats that featured the much narrower trailing edge of the keel that had to be built as an add-on piece (the so-called "false keel"). When comparing externally- and internally-ballasted Tritons side by side, the differences in the keel shape are immediately noticeable, at least in terms of width; differences in draft, if they exist, are more difficult to determine, of course, but I've heard numerous accounts that point to up to a few inches' increased draft on the internal ballast boats.

Zach · Post by **Zach** » Wed Jul 30, 2008 11:13 am

Thanks Tim!

I'll plug away at the inner set of lines and see what happens.

Zach

Ganges #363 · Post by **Ganges #363** » Wed Aug 20, 2008 12:51 pm

Perhaps you are only referring to East Coast boats, but my WC boat #363 has encapsulated ballast. It seems to me that all WC boats are built that way, and there are WC boats numbered below 100.

Bill
Ganges #363

bcooke · Post by **bcooke** » Wed Aug 20, 2008 2:48 pm

Yeah, I think that is a given.

The fact that Aeromarine were issued 'batches' of hull numbers makes the sequential order of Triton production rather problematic. More importantly though, Aeromarine did a lot of things differently from Pearson which is one reason why Pearson ended the relationship in 1963. Bristol and Salsaulito Tritons differ in so many ways that they really shouldn't be considered the same boats. They both started with the same lines drawings but both manufacturers used their own interpretations in their final products.

For the Bristol RI produced boats it is pretty clearly established that the hull mold was changed to incorporate internal ballast beginning with #382. Even with the boats sometimes being built out of sequential order, this demarcation is one of the few established certainties in the production history. I should add that I don't have complete information to support this but I think I have enough to be fairly certain.

Zach, I keep meaning to measure accurately but I am quite sure my internally ballasted Triton draws more than 4 feet. My rough measurement last summer was about 4' 5" from the bottom of the keel to the scribed waterline. By pure coincidence, my boat actually floats (or at least it did) right at that scribed waterline. As I think about it though, I have no idea if the scribed waterline is where Alberg initially drew it.

jollyboat · Post by **jollyboat** » Wed Aug 20, 2008 4:40 pm

Tritons are very weight sensitive. A little extra weight will have a considerable impact on how the boat floats. The CCA designed boats with narrow, pushed in bilges have a small displacement foot print when at idle. It does not take much weight to push the boat deeper into the water. With the basic design of the hulls being basically the same combined with a less than exacting production schedule at the Pearson Corp while they were trying to complete a Triton per day it is no surprise that there are such wide varying degrees of floating depths for different boats.

bcooke · Post by **bcooke** » Wed Aug 20, 2008 6:47 pm

My thinking though is that the internally ballasted boats are actually taller - keel bottom to shearline. That is the the keel extends down further to go around the ballast pig which is in the same relative position as the externally ballasted boats. I am only guessing. I will take a measurement from the shear to the scribe line and from the scribe line to the bottom when I get a chance.

bcooke · Post by **bcooke** » Wed Aug 20, 2008 8:03 pm

My curiosity got the best of me and I took a detour by the boatyard.

Picking a point at the aft end of the aft deadlight, the height from keel bottom to sheer is 80.25 inches.

I picked that point by eye because it looked like the deepest part of the keel. The scribed waterline is 27.5" from the sheer on the starboard and 27.75 on the port side. Normal tolerance from the Pearson factory...

Since my boat floated on the scribed line that meant I was drawing roughly 4 feet 5 inches.

Zach · Post by **Zach** » Wed Aug 20, 2008 9:10 pm

Thanks Britton!

The next one is the thickness of the bottom of the keel.

Once we've got a thickness for an east coast internally ballasted and east coast externally... the line drawings will make more sense. Not exactly clear which line goes with which down there...

By the way, the plans call for a weight of 7040lbs for 382 and up (Internally ballasted.) 6930lbs for the externally ballasted, deeper keeled boats.

The line plans say the externally ballasted keel is 1.30 inches deeper (relative to the sheer line) than the wide keel on 382 and up.

There are two LWL's drawn on the plans. One 2.85in above the other.
The bold (lower) line I believe to be that of the internally ballasted, as their line at the bottom of the keel profile is bold.

Total fudge factor = 3.15 inches...

The internally ballasted keel drafts 46.60in according to the plans.
The externally ballasted 50.75 inches.
50.75 is the maximum spread, 46.60 the minimum.

So... If I've got this straight, the lighter weight externally ballasted boats draft 4 inches more than the heavier internally ballasted ones.

The plans call out 3017lbs for the lead... but I do not know if they used the same mold or not.

(All these measurements are eyeballed half a station aft of #7, where to my eye things look deepest... but since I don't have a deck to look at... I'm not sure if this coincides with your measurements.)

Hopefully in a few more hours of modeling (Once I get the rudder and stuff imputed...) I'll have some facts and figures of actual wetted surface area!

I believe I read a Pearson press release somewhere that Tritons came off the line a lot closer to 8400lbs. The drawn lwl waterplane (don't know yet if it is the bold or light one...) is around 15187.00 inches^2 Or 105.465 square feet.

So... 105.465x5.34 (1 square foot of salt water) is 563lbs.

So... if they really are 8400lbs (going off 7,000lbs as a baseline...) they will sit 3 inches lower in the water, or draft 3 inches more.

These numbers are off... because the plans list a waterline of 20 feet 6 inches. My drawing scaled to 24 inch stations is 20.4 inches long... So add a fudge factor, but ought to be close enough for working around...

P.S. I had a yo-duh moment about the Constellation rudder a few days ago... The drawing doesn't have a scale but it lists overall length of the boat and has stations drawn in. Ought to be able to extrapolate from there and get close enough for government work. Haven't tried laying the line plans over the originals (Not sure how to do that in Solidworks yet...)

Also looks like some area was added or taken away from the lower half of the rudder on one or the other... Wacky.

My brain hurts.

Zach

Zach · Post by **Zach** » Wed Aug 20, 2008 9:13 pm

Oh...

Measured from the bottom of the keel at the deeper of the two, and got 77inches. Add a few inches depending on the toe rail style.

I'll have to go back through this again... at the moment it gets a "Theoretical" stamp. Even if it is just the plans... who knows where the boat strays from them!

Zach

bcooke · Post by **bcooke** » Wed Aug 20, 2008 11:08 pm

I would be surprised if Pearson stuck right to the lines plans too. It was probably more of a guide than anything.

Something tells me they were a little liberal when they created the mold. It might have something to do with the fact that the two sides of my boat are clearly not the same and are inches apart in some cases.

Measuring the thickness of the bottom of the keel is going to be problematic. If they couldn't settle on a thickness for the hull I don't see why they would stick to an accurate figure at the bottom of the keel either.

It is probably also going to vary depending on where on the bottom you measured as well. I think about 2 feet back from the front edge I drilled several test holes and I am guessing 2-3 inches throughout. I still have one hole open at the aft end for drainage and I can check that.

Zach · Post by **Zach** » Wed Aug 20, 2008 11:09 pm

One more before I pass out...

Anyone see the center of gravity and center of buoyancy marks on that drawing? I am inclined to think that they are the two round dots on station 7... but do not know for sure.

I need to take the time to overlay the drawings that are out on the net and see if I can sync the deck to the shear line and draw in the bulkhead locations... Sure would be nice to have Albergs thoughts on where things are, rather than resorting to fudge factors and guesstimations! Example: where to put the heavy stuff... (Grin)

Thanks for your thoughts everybody. Fun discussion, even if a tad theoretical/boat-nerdery...

Zach

bcooke · Post by **bcooke** » Sat Sep 13, 2008 10:31 am

Zach, I heard a good idea recently.

Someone needs to loft out a full sized half-breadth pattern of the Triton so we can match it up with the actual boats. I am pretty sure it will be way off and neither side will be the same as the other. Might be fun.

Over the hours I have spent sanding the hull, I have had a lot of time to contemplate the hull shape and I am pretty sure it isn't what C. Alberg had in mind. For instance, I don't think the top six inches on a good portion of the hull was supposed to flair out to meet the deck.

Oh, and on closer evaluation it appears that my boat draws something more like 4' 8".

Measured from the bottom of the keel at the deeper of the two, and got 77inches

That would be about right then. My extra three inches is probably the extra keel thickness to wrap around the ballast pig.

Zach · Post by **Zach** » Sun Sep 14, 2008 7:21 pm

Britton,

Yeah that would be pretty cool! I guess the way they do lofting of boat hulls is to draw everything out on the floor...

Wouldn't be a huge deal to take a station number and build a form out of it, measuring from one of the center dots and making a tick stick... Could even do some fancy stuff with a built in protractor for measurements radiating out every few degrees.

Here is the difference between the ear shaped stock rudder, and the constellation rudder drawn on the Mark 2 plans for the Museum.

Keep having trouble laying different line drawings over each other... aspect ratios are just a touch different, and they'll be accurate on station lines, but the buttock lines seem to be off... even though the hull lines lay on top of each other.

Got me as to why...

Zach

Harry James · Post by **Harry James** » Fri Dec 12, 2008 12:16 am

I haven't posted for a while but I thought I would throw in a WC comment on keels. As commented the WC keels were encapsulated from the start but I don't think they were wide. They were able to build the narrow aft piece of the keel as part of the boat and not an after thought because the hull was built in half's something that I have never seen mentioned. The first few Aeromarine hulls were apparently very heavy, Jim Harts #94 is almost a ton heavier than my #144. My boat was the 11th built by Aeromarine give or take. It is light weight coming in around 6900 with anchor and batteries and no water on board, engine out. This weight held in to the high 300's at least, #362 "Patience" weighed in at 7K without cruising stores aboard according to Debbie Weeks.

JonnyBoats · Post by **JonnyBoats** » Sat Dec 13, 2008 9:01 pm

I'm digitizing the line drawing of the triton to turn it into 3d...

Can you tell us a little more about how you are doing this? Also will you be sharing the file when you are done?

Zach · Post by **Zach** » Sun Dec 14, 2008 2:32 pm

John,

I took a .jpg picture of the Triton line drawing I found on the web, and imported it into a program called Solidworks.

Then I adjusted the dimensions of the picture, to be full scale by getting the station lines the correct distance apart. (Forgetting what they are on the drawing...)

Then I laid out the station lines by drawing #1 on plane 1. #2 on plane 2... etc. Once I had the station lines drawn, I had the curve of the hull. Then I used a skin tool, which played connect the dots and turned it into a 3 dimensional model.

That gave one half of the forward section of hull, and one half of the back section of hull. I mirrored each... and came up with this.

http://bp3.blogger.com/_O-gL52GSgdo/SJH ... +rough.JPG

http://bp3.blogger.com/_O-gL52GSgdo/SJH ... /rough.JPG

Then my trial for Solidworks 2008 ran out, around the same time I was trying to get the transom drawn up. (Its got a ton more curve to it than I ever thought...) Put it on hold, and have been waiting until I got a seat for 2009, it'll be next week before I get the disks. (Grin)

Yup... once I've got it cleaned up I'll be sharing it. Got some dimensioning issues at the moment... like how wide the radius is of the stem. As its drawn I've got a gap between the two halves of the hull. I'll have to do some real measuring on my boat to see how accurate the line plans are to my drawing... and the real boats.

Zach

Triton 53 · Post by **Triton 53** » Mon Dec 15, 2008 9:42 am

I messured Alli-Ann hull #53 yesterday and came up with 4'3" to 4"6" at the true water line. (I knew there was a reason I have not power washed the hull yet) The differance between the port and starboard water line height is due to the pitch of my driveway and we did not put a level on the boat when we put it on the stands. The true water line is about 2" above the lower scribe line.

Pete

Harry James · Post by **Harry James** » Thu Jan 08, 2009 5:00 pm

On the subject of lines, Bruce Hallman did a Freeship drawing on the Triton for me, posted at his Flicker site

http://flickr.com/photos/hallman/311106 ... otostream/

When I built my new rudder I carried out the bottom rather to give a little more area.

http://tritonclass.org/mir/144ps2.jpg

HJ

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