Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[rmaddock]

If I've got an old photo of a boat (and I have) can I take measurements from it?
I know how long the hill is but the boat's at an angle and seen slightly from above. Are there tricks of geometry available to get a good idea of how big things were? I'm specifically interested in how long the bowsprit might have been.

[Roadrunner]

What boat is it of?, you will be surprised what information can be found on old boats with a little bit of guidance also if there are plans available of that boat, I've yet to not find a boat without plans somewhere even if only rough line drawings its usually enough to get started with.

Taking measurement from photos is very tricky to get right as things like perspectives can change the dimensions, in some cases seriously.

Is this for a projects or just general interest?

[boatmadman]

The nearest you will get with this angled photo is, if there is something in the picture of a known (or closely estimated) dimension, then you can use this as a base for getting other dimensions.

Also, if you have a known vertical dimension ( or closely estimated), use this to estimate the length of the hull in the pic, then, knowing the length of the original nobby you can calculate the angle at which the picture was taken.

Then, using schoolday maths you will be able to get dimensions from the pic using cos(angle) = angled length/known length.

Failing that, I have a book that has a set of pictures and a lines diagram of a Manx Nobby which I believe were similar to the Morecambe bay prawners.

This book says that the bowsprit on the Manx Nobby was 15 to 16 ft.

Let me know if you think it may be useful.

Ian

[dreadnought72]

Photogrammetry is your friend!

There are many ways to get accurate dimensions from a photo. What's the issue, and - more importantly - can you share the photo?

Andy

[rmaddock]

Photogrammetry is your friend!

There are many ways to get accurate dimensions from a photo. What's the issue, and - more importantly - can you share the photo?

Andy

I don't know if I can, but I will and apologise to anybody whose copyright I might infringe.
The boat in question in "Hearts of Oak". She was built in Ulverston in 1912, where I live...hence the interest. This is how she was:

She has been rescued and "restored". She now looks like this:

Now, to my amateur eye, it looks like the rigging is not identical to the original. To be fair, from other pictures I've seen I don't think there was anything left of the rigging to copy from.
My first question was about the length of the bowsprit....it looks distinctly longer in the old photo. Similar questions about the mast height etc etc might follow on.

Now, there are plenty of (apparently) parallel lines in the picture so I thought it might be possible to calculate the angles in the picture and thus do a bit of geometry and, based on the known length of the hull (34'), work out some other dimensions.

Of course, failing all of that I could just plump to build it as it is now but it'd seem a bit of a shame.

Cheers!
Robert.

[boatmadman]

Robert,

I just had a look at the as was photo, you can get quite a lot of reasonable dimensions off that one. First you need to find out the average height of women around the time 'oak' was built, then use that to guestimate the dimensions.

From the look of the photo, the length of the sprit looks to be in the region of 15ft as per the manx nobby I mentioned.

I have found a couple of small pics of a similar rig set up on a manx lugger and a Truro oyster boat, but they are only small. I cant post them on here due to copyrights, but if you want a gander I can bring the book to the clubhouse sometime - let me know.

Ian

[rmaddock]

I can bring the book to the clubhouse sometime

So have I actually met you yet Ian? I know we popped in last weekend (and paid our subs) when the regatta was happening but I didn't know anybody from Adam. I'm afraid that we were up Dow Crag in the rain today so no boating....and we're in a wedding in Paris next weekend.....it's a tough life 

[kiwi]

Hi,
from my experience with drawing from photos, that bowsprit has got to be 15 to 16 feet long, and the rigging is definitely different.
cheers
kiwi

[rmaddock]

Hi,
from my experience with drawing from photos, that bowsprit has got to be 15 to 16 feet long, and the rigging is definitely different.
cheers
kiwi

Thanks Kiwi, it's good to know it wasn't just my warped imagination 

[boatmadman]

So have I actually met you yet Ian? I know we popped in last weekend (and paid our subs) when the regatta was happening but I didn't know anybody from Adam. I'm afraid that we were up Dow Crag in the rain today so no boating....and we're in a wedding in Paris next weekend.....it's a tough life 

Not yet Robert, I wasnt there last week, no boating this week due to a charity run. It'll be a couple of weeks till I am there on a sunday next, am off to Cypress, it sure is a tough life!

[LarryW]

HI KIWI hope you are well ,?,  just a couple pictures of BR AND AT black rose on the edge ,must reduce sail to suit
 gusty conditions , Alma's first outing went really well      looked Nice on the water,    SO WHATS NEXT with your boats
any new plans to go for your designs seem to work look forward to the next one ...cheers LARRY....... OK2