Help trawler confusion - Page 5

Underway · 05-06-2015, 09:26 PM

Quote:

Originally Posted by Marin

While GB certainly set a high standard for construction quality I think their real contribution, starting in the mid-60s, was consistency. Where many of the so-called Taiwan Trawlers varied all over the map in build quality within the same model due to the way the manufacturing and assembly was farmed out, American Marine, first in Kowloon and then in Singapore, turned out boat after boat identical in build quality. First in wood and then in fiberglass. Not just their Grand Banks line but their Alaskan line as well (which was only made in wood).

If anything sets GB apart I believe it is this consistency from boat to boat starting in 1966 up through today. Not that other makes do not exhibit the same degree of consistency. But I believe American Marine was among the first to set such high standards of consistency among production cruising boats.

One of the worst bottom blistered hulls I've ever seen was on an early 80's Grand Banks.

**FlyWright** · 05-06-2015, 09:27 PM

Quote:

Originally Posted by Art

Don't forget that tanks can be crushed inward (made smaller for close quarter maneuverings) by applying ample suction (i.e. negative-inside-pressure) via one opening having sealed all other openings.

I can't imagine the amount of vacuum required to collapse a mild steel fuel tank, but I have great confidence that several folks here will know precisely what is required.

RT Firefly · 05-06-2015, 09:34 PM

Greetings,
Mr. FW. Depending on the geometry of the tank and how it's well its air tight integrity is maintained during collapse even a cheap vacuum pump might be able to collapse it significantly. Absolute vacuum is only one atmosphere (14.7 psi). It's not really an "amount" of vacuum. Vacuum is vacuum. One can achieve 2 atmospheres of pressure (dive to 66' underwater is it?) but it is not possible to achieve -2 atmospheres of vacuum.

Rebel112r · 05-06-2015, 09:35 PM

In regards to collapsing a fuel tank, I have seen a 12 volt barrel pump, put a significant dent in a 500 gallon round storage tank. That is what happens when you forget to open the vent. The sound it makes gets your attention.

**FlyWright** · 05-06-2015, 09:41 PM

Quote:

Originally Posted by RT Firefly

Absolute vacuum is only one atmosphere (14.7 psi). It's not really an "amount" of vacuum. Vacuum is vacuum.

YGTBFSM!! You've never seen a vacuum gage provide a quantified measure of vacuum?

You just seem to want to argue semantics. Read a book instead.

Art · 05-06-2015, 09:45 PM

Quote:

Originally Posted by FlyWright

I can't imagine the amount of vacuum required to collapse a mild steel fuel tank, but I have great confidence that several folks here will know precisely what is required.

If she's old, already leaking, and afflicted with rust otherwise... suck, baby suck! Diesel tanks seem to have little to no flammable potentials under nearly any conditions.

I can not recall from where I got info on this vacuum technique... believe it was Tollycraft forum... but, as I remember the results sounded great for minimizing tank size in a tight space. The owner then put in slightly down-sized tanks for EZ fitting. If I ever need to do so on our gas powered Tolly; I'd fill the tank with water and suck the water out with a really big pump. Don't see how it could explode filled with water only??? I'd sure do research before doing so on a "gas" tank.

Will be interesting to hear comments from others!

Happy Tank-Removal/Replacement Daze! - Art

**FlyWright** · 05-06-2015, 09:47 PM

That reminds me of that "Aha!!!" moment in my young daughter's life. She was about 4-5 and we were talking at our regular 6PM family dinner about the temperature of the winter air back east. We were discussing the sub-zero temps and my daughter had this deep thought look on her face. Then it changed to one of wide-eyed understanding! "I never thought of something less than zero before. Things really can be less than zero!"

It was something I had never seen the same way, but she showed me her way. At such a young age, it was a real eye opener for me, too!

Marin · 05-06-2015, 09:52 PM

Quote:

Originally Posted by skidgear

One of the worst bottom blistered hulls I've ever seen was on an early 80's Grand Banks.

American Marine/Grand Banks had trouble with their hull layups in the later 70s-early 80s because they were not following the hull layup process that the man who got the company into fiberglass in mid-1973 had set up.

Howard Abbey designed and built the original molds for the GB36 and 42, and those to models were switched to fiberglass construction in mi-73 in their Singapore yard. For the first year every GB36 and 42 hull layup was personally supervised by Abbey. He quit the company in mid-74 or thereabouts when he suspected the company was on the road to financial difficulty, which it was.

After his departure their hull layup processes slipped from Abbey's high standards. The situation eventually got so bad that the company brought Abbey back twice in the ensuing years to correct all the problems and get the hull layup process back on track. The second time he returned he found things being done so poorly that he told them how to correct the problems and then, after suggesting that they not call him ever again, he left.

At least this is the story as told by Abbey in an interview I read.

Whether or not these hull layup difficulties had anything to do with the problems you observed on the early 80s GB you mentioned I have no idea.

Our own GB36 is from the first batch of fiberglass GBs and its hull layup was personally supervised by Howard. It's probably overbuilt given the newness of using fiberglass for larger boats back then, but it's an incredibly strong hull, something which we have had an occasion to prove.

RT Firefly · 05-06-2015, 09:53 PM

Greetings,
Mr. FW. Of course vacuum can be quantified but only to 1 atmosphere. I suspect we are discussing the same thing.
http://en.wikipedia.org/wiki/Vacuum
Indeed, my high vacuum technique is a bit rusty but I will fore go the literature search.
Ah....I see where your coming from. I suppose the most accurate answer would be pump on it until it either collapses sufficiently or ruptures to the point of losing vacuum. Gotcha.

Capt.Bill11 · 05-07-2015, 05:30 AM

Quote:

Originally Posted by Art

Don't forget that tanks can be crushed inward (made smaller for close quarter maneuverings) by applying ample suction (i.e. negative-inside-pressure) via one opening having sealed all other openings.

Let me get this straight, you're claiming you can crush a properly baffled square/rectangular fuel tank with vacuum, install it and then re-inflate it back to its original shape!?

Oh I'd pay to see you try that.

RT Firefly · 05-07-2015, 05:51 AM

Greetings,
Mr. 11. I don't think Mr A. is saying one can re-inflate the tank but one may be able to deform it enough to allow "wiggle room" for removal. As to the re-inflation, I'd pay to see that as well. The fact the tank is probably leaking would mean sealing it sufficiently well to allow vacuum deformation and would probably be more trouble than actually cutting it up with a saw and removing it in pieces. I wouldn't want to be near such a tank if a vacuum collapse was attempted. I have witnessed several implosions in my day and...well, stand back. Waaay back.

Art · 05-07-2015, 06:57 AM

Quote:

Originally Posted by RT Firefly

Greetings,
Mr. 11. I don't think Mr A. is saying one can re-inflate the tank but one may be able to deform it enough to allow "wiggle room" for removal. As to the re-inflation, I'd pay to see that as well. The fact the tank is probably leaking would mean sealing it sufficiently well to allow vacuum deformation and would probably be more trouble than actually cutting it up with a saw and removing it in pieces. I wouldn't want to be near such a tank if a vacuum collapse was attempted. I have witnessed several implosions in my day and...well, stand back. Waaay back.

Correct RT - No re-inflate mentioned or presumed possible for metal tank. Wiggle room for tight space removal is the sole intent. Cutting up a diesel tank is probably fairly worry free so long as means of cutting was not too hot and tank had been drained/flushed correctly... maybe filled with CO2 ?? Cutting up a gasoline tank = facial reconstruction... if you're lucky to live.

DutchProf · 09-02-2016, 11:18 PM

Interesting - I tried to look at that boat - traveled to CT, only to have my appointment cancelled after touching down at Bradley. Seemed as if the broker was not interested in showing the boat to me, even after I contacted him later. Listing finally disappeared relatively recently - I'd be curious to know what happened - Boat was known as 'Tuesday Afternoon' - I was willing to travel and pay close to list - was a strange experience...

ben2go · 09-05-2016, 09:31 PM

Quote:

Originally Posted by DutchProf

Interesting - I tried to look at that boat - traveled to CT, only to have my appointment cancelled after touching down at Bradley. Seemed as if the broker was not interested in showing the boat to me, even after I contacted him later. Listing finally disappeared relatively recently - I'd be curious to know what happened - Boat was known as 'Tuesday Afternoon' - I was willing to travel and pay close to list - was a strange experience...

It may have been sold and they failed to contact you in a timely manner.