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View Full Version : Bore an 8" X 96" pipe?



tiptop
07-30-2008, 07:29 PM
Well I changed plans on the shop addittion, so I submitted a new set to the county and that is on hold for a bit. So then a local fisherman got a hold of me because he needs to change out his sonar unit. The old one gave up, so he bought a new one. The unit is installed in an 8", schedule 80 pipe that is welded to the lower deck and just in front of the keel. The problem is, the new one requires a 8.25" pipe. The boat is 86' long and he isn't schuled to have it hauled out for maintenance until next year. So he wanted to know if this pipe could be bored out with the boat in the water. It looks as though the lower 6' of the pipe are submerged at best. He thinks the tolerances on being true for the length of the bore would have to be within .050 of an inch. I have some pictures of what it looks like and of course want all the feedback I could get on if this looks feasible.
This is looking down in the bilge at the transducer. You can see the flange on the pipe that it mounts to.
http://photos.imageevent.com/aatiptop/covelocatools/websize/Covelo_%20Ca%20tools%20019.jpg

Here is a better shot of the mount and pipe.
http://photos.imageevent.com/aatiptop/covelocatools/websize/Covelo_%20Ca%20tools%20020.jpg

This is a shot to show the clearance above the unit. There is about 3' from the flange to the steps.
http://photos.imageevent.com/aatiptop/covelocatools/websize/Covelo_%20Ca%20tools%200213.jpg

Here is a shot of the new unit with its flange.
http://photos.imageevent.com/aatiptop/covelocatools/websize/Covelo_%20Ca%20tools%200223.jpg

tiptop
07-30-2008, 07:35 PM
This one shows most of what the new unit looks like.
http://photos.imageevent.com/aatiptop/covelocatools/websize/Covelo_%20Ca%20tools%200233.jpg

Unfortunately, the flange is not very square with the pipe and I believe this is what caused the failure of the last one. It would need to be trued up so a guy could mount a boring set up to it.
It would be an interesting project, my main concern is boring under water and not being able to see what is happening. Any help you can think of would be appreciated. Thanks, Jay

Steve Steven
07-30-2008, 09:16 PM
That doesn't look like 96" length of the probe, did you misprint that? Looks more like 36" fron the picts.

I work on these some, the ones I am familiar with all have a "sea valve" at the hull, so you can pull it off the flange. Looks like this one doesn't? So the top of the flange is above water line?

If I were to try to bore that, I would have an upper and lower bearing, cutting a hole in the steps to get the boring bare long enough to reach. As you said, it will be difficult to align the rig so you can keep on center of the pipe while boring, have to use the outside as a guide while setting up. Not easy.

Steve

wierdscience
07-30-2008, 10:18 PM
If the emitter is smaller than the 8" ID,what about making up a new flange and 36" long top "can" and then cutting off and welding onto the old stem?

If that were doable maybe make it a tight slip fit on the od of the old stem so it lines up straight before welding.

Rustybolt
07-30-2008, 11:24 PM
Instead of boring out an eight inch pipe, why not turn down a 9 inch pipe? It might be easier to have someone roll a piec of steel the right size.

winchman
07-31-2008, 03:33 AM
Fashion a cap with appropriate sealing material to fit the hull around the pipe opening. Have a diver take it down and hold it in place while you pump the water out of the pipe and the cap. Now it's dry inside the cap, and the water pressure holds the cap tightly in place. Use some long straps for insurance.

Cut the hull around the 8" pipe with an O/A torch, and remove it. Fit the new larger pipe in place, and weld it to the hull from the inside. Remove the cap.

It might be good to have a valve on the cap so you can fill the pipe with sea water to check for leaks before removing the cap entirely.

Why in the world would they make the thing to require a non-standard pipe?

Roger

derekm
07-31-2008, 04:07 AM
posting error please see entry below

derekm
07-31-2008, 04:11 AM
I have a solution that works with the 3ft clearance , the 8ft pipe length, is self guiding, does not require a diver, but it does require 12ft of draft under the boat and the ability to make a 12ft shaft with keyway along its length. Its not cheap.

It involves making a cutter head that travels along the driven keyway shaft. The shaft with a bottom bearing and spacer to fit the bottom of existing pipe size is "fished" into the pipe from underneath the boat (a rope work exercise).

Derek

GKman
07-31-2008, 04:33 AM
It's hard to imagine anything above it I wouldn't sacrifice to get working clearance. Good luck.

crancshafter
07-31-2008, 05:48 PM
I have a solution that works with the 3ft clearance , the 8ft pipe length, is self guiding, does not require a diver, but it does require 12ft of draft under the boat and the ability to make a 12ft shaft with keyway along its length. Its not cheap.

It involves making a cutter head that travels along the driven keyway shaft. The shaft with a bottom bearing and spacer to fit the bottom of existing pipe size is "fished" into the pipe from underneath the boat (a rope work exercise).

Derek

#1 My hope is that you have bilge pumps to take care of the water coming in:eek: if not.
#2 You have to be friend with the innsuranse company:confused: ( wery good friend)
#3 And all the guy's in the Coast Guard are your best friends ever:o
#4 Dry Docking not cheep but compared to #1-2, well....................

sconisbee
07-31-2008, 06:24 PM
well there is a way i can think of, but cant quite get my head around it right now too tired so ill check back tommorow, but it would depend on the current surface quality of the existing tube and also assumes that the opening of the tube is above water line.

dsharp
07-31-2008, 07:05 PM
I would think if he can afford a sonar unit he could afford the haul out to install it correctly.

Guido
07-31-2008, 08:39 PM
Fab up a dummy tool, and measure the exact nominal ID clearances inside the existing drop pipe. Just might be a case where the brass looking thingy on the new sonde, presents the largest OD. Manufacturer would probably croak, if he found out 0.125 inches had been turned off his sonar tool OD?

Waterwell pump manufacturers are all the time skimming down the OD's of submerged vertical turbine pumps. Gotta make 'em fit. YMMV

G

GKman
07-31-2008, 08:40 PM
I would think if he can afford a sonar unit he could afford the haul out to install it correctly.

Where does it say he doesn't want it installed correctly? I would think the results not the method would establish correctness.

tiptop
07-31-2008, 09:41 PM
I went down to the dock to look at it again today. The owner was not there but one of his hands was. He said he thought the pipe was about 5' in length. That helps quite a bit, but the he said he thought all but about a foot of that was under water. They had a diver install a basketball type bulb to seal it off so they can take the old one out so when I get time I will get some shots of it out of the tube. The deck hand is from the east coast and he said what they do back there is along the line of what winchman said. Take a 55 gallon plastic barrel and cut it to the shape of the hull, seal it and run straps around the boat to help hold it. The boat is 82.5' long and is 25' wide on the deck. There really is a very good way to replace the pipe without dry docking it as it is in the engine room which is cramped at best and the deck you see in the hole where it is mounted is a sub deck. the deck is double there with about a foot between them and the front of the keel starts there also. I think if I can face off the flange, true to the pipe so I have a decent mount there ought to be a boring bar arangement that can be fabbed up. Bearings on each end sound very good. They have lots of heavy duty hydraulics on the boat already so it could be driven by that which would be nice to slow the cutter speed down without gearing and or belts. I guessed somewhere between 60 and 140 rpms depending on the type of tooling. I have a bunch of stellram that would work nice if the set up was ridged enough heavy cuts could be made. Sorry to be long winded, just some thoughts I had during the course of the day. As always suggestions are more than welcome here. Jay

andy_b
07-31-2008, 09:56 PM
I went down to the dock to look at it again today. The owner was not there but one of his hands was. He said he thought the pipe was about 5' in length. That helps quite a bit, but the he said he thought all but about a foot of that was under water. They had a diver install a basketball type bulb to seal it off so they can take the old one out so when I get time I will get some shots of it out of the tube. The deck hand is from the east coast and he said what they do back there is along the line of what winchman said. Take a 55 gallon plastic barrel and cut it to the shape of the hull, seal it and run straps around the boat to help hold it. The boat is 82.5' long and is 25' wide on the deck. There really is a very good way to replace the pipe without dry docking it as it is in the engine room which is cramped at best and the deck you see in the hole where it is mounted is a sub deck. the deck is double there with about a foot between them and the front of the keel starts there also. I think if I can face off the flange, true to the pipe so I have a decent mount there ought to be a boring bar arangement that can be fabbed up. Bearings on each end sound very good. They have lots of heavy duty hydraulics on the boat already so it could be driven by that which would be nice to slow the cutter speed down without gearing and or belts. I guessed somewhere between 60 and 140 rpms depending on the type of tooling. I have a bunch of stellram that would work nice if the set up was ridged enough heavy cuts could be made. Sorry to be long winded, just some thoughts I had during the course of the day. As always suggestions are more than welcome here. Jay

i'm not sure if you're ready, willing, or able to answer this, but i have to ask (and no, you don't have to answer). just how much does a boat owner pay for a job such as this? it sounds like a real PITA, and something that could be very expensive if you fudged it up.

andy b.

mark61
08-01-2008, 06:20 AM
My question is why didn't the boat owner measure BEFORE he bought a new 1 to make sure he did not end up with this problem? Why not just return it and find 1 that fits already?

mark61

thistle
08-01-2008, 06:59 AM
fishermen do not clean anything they do not oil or grease anything , they also dont liketo measure things .
if it does not fit as in this case , it is likely they will clean, grease, then hit the offending transducer with asledge hammer.

Michael Edwards
08-01-2008, 07:34 AM
He said he thought the pipe was about 5' in length. That helps quite a bit, but the he said he thought all but about a foot of that was under water. They had a diver install a basketball type bulb to seal it off so they can take the old one out so when I get time I will get some shots of it out of the tube.

You need to get an accurate measurement of the water line on the pipe. If there really is a foot of pipe above waterline, then it was a complete waste of time and money to plug it with the bulb. It would also make your job much easier. Not only is plugging the pipe now, cart before the horse, if the top of the pipe is under the water line the plug will have to come out and a different one installed so the whole length of pipe can be reached. Hauling out a boat that size isn't cheap, so I can see why he is looking for alternatives.

ME

Bob G
08-01-2008, 08:30 AM
Hi All, Because I don't understand all the other concerns I will confine my comments to boring the the pipe ID.
Back in the 1950's. while working in the tool room at Thompson Products, a major manufacturer of jet engine parts, we made Pack Reamers that were about 3" in diameter. They consisted of a boring tool with wooden bearing blocks ahead of the cutter that fit the "before ID" and another set of wooden bearing blocks following the tool that fit the finished the finished ID.
I checked all my reference books but could not find any info. Also Googled "Pack Reamers" and found references but no photos.
I think they were used to bore the main shaft for an axial flow jet engine. They must have worked because we reworked used ones and had repeat orders for new ones.

Have Fun,
Bob G

sconisbee
08-01-2008, 02:51 PM
Ooops, i had forgotten about this thread (busy day) anyway, my suggestion was going to be pretty much exactly what bobg refered to, some kind of traveling steady with a bearing in the middle and the od the same size as the current pipe id (assuming current pipe is relitivly clean on the inside) boring bar that attaches to the bushing/rest center bearing then a bearing on the top flange in the same way as normal line boring and then machine away, granted not as straight forward as it may sound but it does work, did a job last year on a rudder tube on a large ship in a similar way.

bikewrench
08-02-2008, 05:21 PM
You may need to enlist a diver for this one but that should be a simple problem. I am a scuba diver and would do this for 50$. Just go to local dive shop,( fishing boats and dive shops are all near water) and ask if a Divemaster wants to make fity bucks. He/She can go under and plug hole from bottom with cap and rubber gasket,must be simple cap, You have very little leverage under water,but the water pressure will push up when you vent inside.The right way is called a cofferdam and has a small eductor/jet pump that uses water to draw a suction on the pipe or hull. Once the opening is plugged you can pull the old unit and measure, May be the problem is fouling/barnacles/rust in wich case it may simply need cleaning out polishing with a long dieasel engine ball hone and recoating with bottom paint. No expert but been diving professionally for 10 plus years and seen the bottom of lots of boats. Most are a mess even when the top is pretty. Keep us posted as to how this turns out, could get exciting fast if done poorly.