Get Home (Maneuvering Only) 2nd Engine

neworleansrich said:

The problem with all these forums are all the useless and inane comments unrelated to the original issue.

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LOL, maybe your right, Rich, although to admit that a few of the insane and unrelated ideas expressed in these forums are being incorporated into my boat right now. Somewhere between the lucidity and madness, experience and imagination, and the qualified and ridiculous is the answer to the question I'm too embarrassed to ask.

neworleansrich said:

So what do you think guys? Repowering would mean cutting a hole in the side of the hull to get the 12v71’s out. One boatyard thought they could do it for around $200k. The boat is probably worth $325k and may be worth no more even if it was repowered. The 12v71’s are in ok shape, but running them slow is not helping their lives. Any downsides? alternatives?

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The problem with all these forums are all the useless and inane comments unrelated to the original issue. I know it's hard to believe, but he has considered selling it and buying something else.

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Sorry if my posts might not have been on the "folding prop" target, Rich. I was more responding to your first post/last para (quoted)... especially the overall idea of downsides and alternatives

-Chris

Chop a hole in the side may be fine for steel or aluminum.

A GRP boat would be too hard to engineer the patch layup.

Probably the boat could be run as a dock condo , but doubtfull it could ever go to sea again.

FF

Over the years I have seen a number of boats in yards with a hole cut out of the side for removing the fuel tanks. Have no information on how they handled after the repair of the hull. You have raised an interesting question.

Marty

Done all the time...there's a yard that does Grand Banks fuel tanks out the bottom.

A glass boat chopped to pieces with a chainsaw can be glued back together virtually as strong or stronger if you like and the repair is done properly.

On some glass boats the sides just keep the water out. They are not really structural but on others they are....So if the repair requires additionl strength, much like doubling up lumber around a window.....it could be reinforced...but most fiberglass patches with both poly resin (preferred as same material characteristics) or epoxy will equal or nearly equal the original strength.

psneeld said:

Done all the time...there's a yard that does Grand Banks fuel tanks out the bottom...

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Why would you take the tanks out of the bottom on a FRP recreational boat? Unless it was a YouTube Video? lol Not me, I'm with FF.

Grand Banks fuel tank removal - YouTube

Cutting a hole in the side seems crazy, but I guess from the boatyard's point of view it's the most direct way to get access. No one has ever said the engines can't be removed. It's only been a question of expense.

There must be hundreds of older boats in nice shape with crazy big engines in this same spot. They would be great LRC's or trawlers, but running the engines so slow presents another set of issues.

On this 61 ft Hat, we may try the feathering prop idea for a while if we can find a prop that is not too expensive. The 2.5in shafts are what's driving up the cost. The owner has a spare shaft that we may have remachined to a 2in or 1 1/2in taper end. That way we can get a less expensive prop. The shafts are two piece with a muff coupler so it would be relatively easy to change the back shaft section. Obviously cutting down the shaft reduces the strength, but remember the folding prop side is expected to only be used for maneuvering of get-home.

As someone mentioned above, having feathering props on both sides would be great. You could run either engine alone. Maybe my 48ft Defever would be small enough to make it work.

understand composites...and it's not so crazy...otherwise owning a composite boat is pretty crazy....

look at how many things are glued together in all walks of life...

I can't find it now but I think I read someplace, maybe on a tug yacht board, where someone did remove 6 of the pistons, rods and FI gear to a 12v71 in a tug..... I would think it would one would have to block off the induction and exhaust ports also.

It's not rocket science to cut a hole in the side or bottom - remove the motors - and replace the piece cut out. Most of the expense is not the structural work. Most likely moving plumbing and electrical runs out of the way and replacing.

The cosmetic repair would eat up the most man hours.

If the hole could be positioned below the waterline, perhaps removal might be economically feasible? Think in terms of taking a sawsall and cutting a hole just big enough to drop the motor straight down cutting through the stringers as well as the bottom. Remove the motor. Move the other motor and lower thru the same hole. Move two replacements up thru the hole. Replace the cut out piece and bond in place. Mount the motors and you're ready to rock and roll. No cosmetic work necessary! Only fish will see the scar.

A glass boat chopped to pieces with a chainsaw can be glued back together virtually as strong or stronger if you like and the repair is done properly.

The hassle with chopping a hole in a GRP boat is that the hull flexes.

Even an inspected boat that is required to be overstrength by 400% will flex falling off a wave.

How to repair a skin and retain the same overall flexibility , not the same strength is the question.

Things break at hard spots , hence the dockside restriction .

FF said:

A glass boat chopped to pieces with a chainsaw can be glued back together virtually as strong or stronger if you like and the repair is done properly.

The hassle with chopping a hole in a GRP boat is that the hull flexes.

Even an inspected boat that is required to be overstrength by 400% will flex falling off a wave.

How to repair a skin and retain the same overall flexibility , not the same strength is the question.

Things break at hard spots , hence the dockside restriction .

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So far I've never read of a restriction...

Though older...one of my fiberglass repair books uses a USCG small boat as an example of a fairly major hull repair.

I doubt owners would have it done and yard owners recommend it if it restricted their open ocean movements.

Repower - 74
"At their typical cruising speed of 10 knots, they have doubled their fuel mileage!"

Update

We are taking the Hatteras 61 back to the Bahamas from New Orleans this summer. No re power yet, but we did a back-to-back test where we ran with one engine at 8kts with and without the dragging prop installed.

The difference in fuel burn was almost 20% After that test we went ahead with the feathering prop idea.

The attached photo shows the 32inch Max Prop installed. This prop could be used on either side, so the overall engine hours can be kept similar.

During the trip this summer we will probably go through over 2000gal of fuel; much of it at Bahamas prices. While the payback won't be from one trip, the fuel savings along with savings from decreased maintenance on the "get-home" engine side will add up.

Sorry the picture did not load right side up.

Here you go


Good looking prop porn

Wouldn't that be sweet!! Twin feathering props. . . Wow

I know they're pretty popular in Europe and a little expensive for my tastes!! But one can dream. . . .

neworleansrich said:

We are taking the Hatteras 61 back to the Bahamas from New Orleans this summer. No re power yet, but we did a back-to-back test where we ran with one engine at 8kts with and without the dragging prop installed.

The difference in fuel burn was almost 20% After that test we went ahead with the feathering prop idea.

The attached photo shows the 32inch Max Prop installed. This prop could be used on either side, so the overall engine hours can be kept similar.

During the trip this summer we will probably go through over 2000gal of fuel; much of it at Bahamas prices. While the payback won't be from one trip, the fuel savings along with savings from decreased maintenance on the "get-home" engine side will add up.

Sorry the picture did not load right side up.

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Wow! So what does a 32" max prop cost?
Hollywood

Most of the folding feathering props are made for sail boats.

So the design consideration is lowest drag under sail .

The only feathering prop I know of is the LUKE made in Maine that is an 80 year old design created for Motor Sailors where motor propulsion efficiency was the key.

LUKE is still in business ,,, just a google away.

With access to the to interior hull the repair of a cutout should not be a big deal. What I don't understand is how that would be done with fuel tanks which would normally obstruct side or bottom access. Seem everything would have to be done from outside????

"With access to the to interior hull the repair of a cutout should not be a big deal."

On a metal boat it would not be , but on GRP it would be a nightmare!

The taper required is 6-1 to 12-1 and the lay up would require extrodinary care and skill., temperature and humidity control and probably vacuum bagging to assure a solid job.

Both inner and outer skin would require the same care , and there is NO WAY to assure the job was proper.
X ray , heat signature even drilling a core sample has errors.

Perhaps in a few years with more plastic commercial aircraft , repairing to a standard will be more frequent , and possibly it will slide down to a boat yard

I have a 1985 Chris Craft with 6V92 engines. What I plan to do for long range cruise is add one or two 200 Gal fuel bladders and keep the engine running at hull speed.

These engines can run forever and the Hatteras is a beautiful boat.

Have fun in your crossing ! you will have an awesome time (guarantee)

Francois said:

What I plan to do for long range cruise is add one or two 200 Gal fuel bladders and keep the engine running at hull speed

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Years ago, my brother & I were taking a 42' sport fisher to the Sea of Cortez. The boat only had a total of 500 gals in her tanks so we added two Coke syrup barrels, one in each corner of the cockpit, secured by straps to the inside cleats. Since the fuel fillers were just forward of the cockpit, all we had to do was have a hose long enough to reach the fillers from the barrels. With a hand pump, it was duck soup to top off the tanks when they were down.

Having had a feathering prop on a (not very fast) sailboat used for racing ,it was noticeably less effective than the conventional prop, maybe even less so in reverse. But as a get home or manoevering prop on the rested engine, it should be adequate. Bet the prop swaps get fast with practice.

The max prop on Bay Pelican's wing engine is terrific in reverse with more prop walk to port then the main engine's prop walk to starboard.

I guess it depends on what feathering prop you have. I had an Auto Prop on my 40 ft sailboat and it was way more effective than the fixed prop. For the same RPM and conditions I picked up at least .5 to .75 knots. Had much better push for getting though seas in the pass with considerably less RPM. In reverse it was way better than the fixed as far as thrust. A little less prop wash. The only issue was that it was very expensive.

For those that want an EGT gauge priced in 1/10 of boat bucks.

Have used these and they are both digital and analog.

Best is common wire can be used from the probe to the gauge , not some special factory cut to length EGT wire.

GlowShift | White MaxTow Double Vision Diesel 1500 Pyrometer Gauge with Thermocouple EGT Probe

Edelweiss said:

Wouldn't that be sweet!! Twin feathering props. . . Wow

I know they're pretty popular in Europe and a little expensive for my tastes!! But one can dream. . . .

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I think he's only getting one feathering prop.

FF said:

"With access to the to interior hull the repair of a cutout should not be a big deal."

On a metal boat it would not be , but on GRP it would be a nightmare!

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It's a bit of a messy job. But hardly a nightmare. Jobs like and similar to that are done here in Lauderdale on a pretty regular basis by quite a number of boatyards.

I'm surprised those engines couldn't be extracted from inside the boat. Might have to come out in pieces, and might take some surgery of interior walls and decks, but those double doors at the back of the salon look pretty wide from photos. A bare Detroit V block isn't all that wide when turned 90 degrees. Hmmm.

I'm surprised those engines couldn't be extracted from inside the boat.

Taking an old engine to pieces to deep 6 it is not the problem.

Taking the NEW engine to pieces will require big buck labor to put it together and keep a warrente.

FF said:

I'm surprised those engines couldn't be extracted from inside the boat.

Taking an old engine to pieces to deep 6 it is not the problem.

Taking the NEW engine to pieces will require big buck labor to put it together and keep a warrente.

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What warranty? I'd never repower with a new engine(s). Secondly, the premise in this instance was to run the boat at reduced speeds/power, so the replacement engines would be in a much, much smaller package....probably fit through the hole for the stripped V12 block. If not, make the hole slightly bigger. Chopping a hole in the hull is crazy.

I've actually looked quite closely at repowering a stabilized Hatteras yachtfish or cockpit motoryacht with one mid sized turbo six...say in the 350-400 HP range... driving the two existing transmissions through a splitter gearbox (or a splitter chain drive box from Ramsey Silent Chain). The engine room in those bigger Hatts is begging for that set up. Spectacular stabilized coastal cruiser and live aboard for reasonable money. If you wanna go slow...do it in style.