Ballest for a Marben

Greetings Forum,

Not being anything close to a good science student, darn lucky to muster out of high school, I have found asking those with knowledge saves my butt.

Don't quite know where in the mix this thread should reside. Our 27 foot Marben is a huge roomy boat for the size, with a 10 beam and a 25 foot waterline length. The boat sits quite high even with 1500# of lead installed during construction, in the keel. Just seems to beg for some lower ballast to offset the 'I think I am a little top heavy roll' feel particularly with a following aft or quarter aft wave action.
Bucking or forward quartering the boat reacts well although it is a 'Rocking Horse" as it hinges on the stern, again it seems to beg for some ballast forward of the engine. (just aft of center).
The construction of the boat has the interior floor and decks fairly high so all the above deck weight begins approximately 3'.5" feet above the keel surface. The draft is 3'.6" and has a full keel. In a 40 foot boat all of this would be normal, however this boat when placed next to a 26 foot Tolly sits a foot higher all around and reflect the difference as one or two people move about. The cabin topside has the normal fly bridge configuration/weight associated. We carry 74 gallons of fuel, 48 gallons of H2O in cross wise configuration. The holding tank is 30 gallon to the Port side. We keep this tank at a minimum as it affects the trim if heavy.
I say all of this to give a perspective of the coming discussion.

In the keel area of the boat there is a depression that runs the full length of the boat. If you would, think of a bread pan mold. In other words, you could lay bread pans with their angled sided shape end to end in this depression slot. ( I had one constructed to lay under the engine with absorbent pads to catch the odd drop or two.)

Now we come to the question and discussion. I have access to a large amount of used zinc from a tug boat operation. While zinc is lighter than lead, it is free. I propose to melt the used zinc and pore it into bread baking pans. (Yes, I have a cauldron and a rosebud touch available)
Thoughts on results? One could picture the pans disintegration with the hot zinc, or if lucky, only form in such a way that the pans would become a part of the finished 'brick'. I suppose as a resort, steel cauldrons could be constructed. I am to understand that the pour into a cast iron cauldron will release, will the zinc release from a steel container? Suggestions?

Of course I have no ideal how much weight each bread pan ingot would weigh, only that zinc is at a scale of 7 and lead is at a scale of 10/11 what ever the scale represents, it is apparent that zinc is lighter.
If the weight were to be worth the effort, (A test melt and weigh would tell.) I am looking for 200+ lbs as a goal.
It is intended to proceed with that and of course results would be reported, just thinking a ongoing discussion leading up to that would be interesting.
Should it prove feasible, then additional melting in say a rectangular pan of some size would provide a thick sheet of zinc that could be placed further out beyond the keel area and possibly covered with a plywood surface to lock them in place.
Will be interested in comments, understand, you can not embarrass me, I am too old to fret!!

A.M.Johnson-Ketchikan, Alaska
27 foot Marben- with a dinky little perkins

Can't help you with the zinc question but I'm curious if your Marben ever lived in Cornet Bay and later Anacortes with a name something like Casa Mia or something else with "Casa" in it. A co-worker had a 27' Marben with this name for several years in the late 90s-early 2000s.

All boats are designed to operate on a specific waterline.

Of course that will vary a few inches with loading.

Is your boat floating ON the designed lines , if not why?

A boat with almost a 2-1 L/B ratio is going to move a lot!!

Based on your carrying capacities...I would be more tempted to make a long skinny water tank in the space...200+ pounds would only be less than 4 CF of water so that's only an 8 foot long by 1 foot wide by 6 inch tall tank (add tank thickness).

If still interested in zinc...be very careful melting it...any used zinc can have moisture in it. I have had it blow itself explosively out of confined areas and have heard the same from others. What size raw zinc is available? 200# isn't much...could you just lay some of it in there first to see what happens before you go to a lot of trouble? If right on the keel you should be OK...anywhere else and make sure there's enough structure to support it.

Before you go to all the trouble of constructing molds and melting metal, why not just put sandbags in the area and see if the extra weight does what you expect it to? If it doesn't help, take them out.

As previously suggested, try something temporary first - sandbags, water tanks, or even a couple of people. As to the bread pans: if they are made of steel sheet you should be OK. Steel has a much higher melting point than zinc. Just don't try warming them up with the rosebud!

Do you know other Marben 27 owners? Maybe there is an owners group forum or organization you could see if maybe someone else has already made such a modification, and the results.
Steve W

Just for reference cast lead weighs about 708 pounds per cubic foot and cast zinc weighs about 440 pounds per cubic foot. How many bread pans per cubic foot? Maybe 9 or 10?
This is an interesting experiment. We need to come up with a way to quantify the effect of the ballast so we can really see if it makes a difference. I think there is a stability test that involves heeling the boat at the dock and releasing it. Does anybody know how to do that test? We need a naval architech on this forum.

I don't know anything about Marben's but I'd try going back to the builder and asking him or thru him, the Naval Architect who spec'd up the original design and get their view on adding ballast. If they are ok with it, I'd experiment with borrowed lead ingots or sand bags first...and then make any additional permanent ballast useful by providing it as an extra water tank (custom made to fit the size/shape available) rather than just as inert zinc or lead.

I like the idea of putting something useful aboard instead of just dead weight. Unfortunately water only weighs about 60 pounds per cubic foot and your ballast goes away as you use the water.

Wow!

A really fine response, I will respond. the boat was designed by Ed Monk, To the best of my knowledge, there were 18 of these hulls produced. Of those I am familiar with four being in a trawler design. There were several constructed as small fishing trollers.

To Marin- I recall you mentioning this 'Casa' boat on an earlier post. No, this boat had three prior owners. The earliest name was "Cirrus"

It rides on the water line with the bow riding about two inches above with full tanks. (fuel/water).

I like the idea of sand bags! while the volume will be larger than the space, for a test it makes the best sense. Good call.

With the price I paid for the boat,(Great value!) constructing space designed tank for what I am attempting to gain will not be worth the effort, however, were the boat in a high dollar catagory, it would be the better move. Fuel prices will never go down, so having a horde of fuel is a good thing.

What is exciting is the suggestion on sand bags. I have a project that requires 1/2 doz of60# concrete/sand bags. This amounts to 360# and I will place them in plastic garbage bags in strategic locations and experience the result. Will post in the near future.


Understand all- I have been a wood boat owner all of my boating life till this purchase. Some locally, have stated that I am too prone to the heavy feel of a wood boat over this light hull. It is not unsafe. We do not fear for our safety, it is a comfort factor. We are fortunate to have the space available to consider modifications.

Really enjoy and appreciate all the posters who are willing to participate with knowledgeable or interesting offerings.
Regards,
A.M.Johnson-Ketchikan

Here's another option to the sand bags that would be a lot easier to clean if spilled, and it comes in #50 sealed bags! And its CHEAP

Morton, 50 LB, White Cyrstal Rock Salt, For Water Conditioning Or Ice

A spilled rock salt bag sets up corrosion big time. I would stay with sand bags unless I had a use for he salt bags after my experiment.

Ahhh, my boat gets salt water in the bilge via stuffing boxes at times anyway. So I'd rather deal with a handful of salt which would melt and get pumped overboard vs sand. Sometimes ya gotta pick your battles and not everyone chooses the same.

HopCar said:

I like the idea of putting something useful aboard instead of just dead weight. Unfortunately water only weighs about 60 pounds per cubic foot and your ballast goes away as you use the water.

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Think of the water as emergency reserve....and even when used up, ballasting won't be worse than it is now. Might give another day or 2 on the hook....& if used up and a long voyage back to home port ahead, fill tank with salt water for the home run. Common strategy.....

Well, Sand or salt, I am more comfortable with the Cement/sand bag contained in a black garbage bag keeping it dry for the test period.

1. I need the cement/sand for a project, so if the ballast test works, One could leave the cement bag in the bag, wet them down and when they set, you have a fixed object to place.

2. If there is no benefit from the test, then the project supplies are ready for use in the project.
3. If the benefit is there, then setting about with the melted zinc as originally thought can go forward.
Thanks again. Keep the thoughts coming


A.M.Johnson-Ketchikan

HopCar said:

I think there is a stability test that involves heeling the boat at the dock and releasing it. Does anybody know how to do that test? We need a naval architech on this forum.

Click to expand...

rolling period test

same thing different version

If you look close, this Marben 27 has a set of what looks to be inmac paravanes. You can see them stored just forward and above the gurdies.

Tells you two things I guess. One, she's stable enough to fish. Two, she's rolly enough to have paravanes. I'm not at home right now, but I think there is a (bigger) Marben in the harbour with flopper stoppers as well.

Yachtworld is down right now (strange). But I looked at the YW posting of a Marben 27 that had some photos in the lift. The chines are harder than I thought they would be by your description. I would do the roll test (above) prior to putting on the cement. Then do it again after your ballasting. You may just end up making her roll more snappy if you put weight down too low.

Northern Spy said:

rolling period test

same thing different version

Click to expand...

I agree with doing some testing, both roll period and incline. A short talk with a good naval architect may help.
Maybe you can trade that zinc for lead.
playing with boats is fun

Northern Spy- This is a 27 foot commercial troller.Marben did construct a 32 foot version and to the best of my knowledge, they were all commercial trollers. I know this boat you picture, it was recently sold. It moored about 2 miles from our home. in speaking with Snapper Carson, the then owner, this boat has the same motion when there is no ice in the fish boxes. When there is ice, the weight is compounded as it is aft the fuel tank(s) Also, on these commercial versions, the engine is placed aft of the house and protrudes above the deck level by 1-16 inches.(Engine hatch height) indicating that the overall center of gravity is lower with a floor plan that is lower overall. By the way, the anchor winch on this boat is a commercial grade hydraulic unit that weights 250# the cable and chain mounted on the winch. I'd say the commercial anchor on the boat is at least 35# + That alone is quite a factor as it sits on the bow. The poles are for fishing, and like every commercial troller, paravanes are a part of the mix. Like sailboat mast, the poles act as a counter weight even in the up position, better in the down position without the paravanes deployed is my guess. These fellows are out in waters that pleasure boats don't normally travel on purpose. As to the chine, trust me, these are far more a round bottom boat than a semi-displacement / planing hull. Hull speed being hull speed, 6.5 knots in a neutral tide is what it iile s.
While the two boats, mine and this model are out of the same mold, the after construction results in many telling differences.
The roll test has been down loaded and will be done prior to placing weight in our boat. Surely that is placing the horse at the right end of the conversation. As before, will report results, have to find a couple of stop watches and a volunteer crew. Stand by.
You guys are okay! really enjoy the input and discussion. great forum site.
A.M.Johnson-Ketchikan

Northern Spy and other posters on this discussion, Here are photos of sister boat. The interior is similar, but different as most boat of the same are, This boat has 200 gallon fuel tank and a bigger H2O capacity than our 74 gallon fuel and 48 gallon H20.


http://www.yachtworld.com/core/list...s=Feet&access=Public&listing_id=1007&url=&imc

Are you guys able to view this site? It didn't turn blue.


A.M.Johnson-Ketchikan

Yup that's the one. It's back up now. The dead aft shot lead me astray. Selective memory had me remembering Spy's bottom as it actually looks like similar deadrise. When I see the side pics, she's definitely full displacement.

I look forward to your test results. When I get home I'll take a look at my GM calculations. Mine was pretty snappy when relaunched and empty after repowering. After a few years of re provisioning (placing useless crap back in the lockers) her roll is more gentle.

I had also thought about putting some lead in the bilge (keel box) but I think she'd just get snappy again with the hard chines on my boat.

I used to have a few 2' chunks of railroad track epoxied on the stbd side for list correction. Took them out when I moved some tanks around. Wish I kept them around to play with now.

Aquabelle said:

...and then make any additional permanent ballast useful by providing it as an extra water tank (custom made to fit the size/shape available) rather than just as inert zinc or lead.

Click to expand...

1) Water weighs the same as water. More than air, but not nearly as much as sand, zinc, or lead.

2) If the water is in a tank and intended for use (potable, washdown, etc.), then the ballast effect will vary with the amount left in the tank.

If it is determined somehow that the boat would benefit from added weight near the keel, lead would be the best choice. Zinc (because the OP can get it free) would be an OK choice. Or sandbags could be left in place.

Maybe this episode will give you a clear picture. But before I start, think about this. the Marben you see in the photos has total 200 gallon fuel tank(s)vs our 74 gallon. that constitutes approximately 1500 # when full and that sits in the lower quarter of the boat, along with 30 gallons of H2o more than I carry or 240#. That is a huge difference in weight between the two boats. It stands to reason then that placing 3-350# of weight may affect but not to the degree it must affect this sister boat. I am going to guess that he is experiences less movement in similar sea conditions as our boat. Maybe not, just seems sensible.
Now- with the seating set up being a sofa to the port, and the passenger or first mate seat to the port, when you have a party of four, one, the male guest, usually the heavier situated, the boat will travel with about a 3 degree list to port, even with the wife sitting centerboard (little thing ) Then if I, the Master and Commander, choose to move about, the list can easly move to 5-6 degrees till I offset once again. I have found that if I shift the 6hp outboard from Port to Starboard along with the fuel supply, the list is reduced to almost nil (not including my moving about). So I have installed a outboard bracket on the railing on both sides of the boat, shifting the outboard as required to achieve the current required balance.
Again all of this conversation rotates around the issue of comfort, not safety.
This boat is not going away.

Regards,
A.M.Johnson
When I was a boy I was told that anybody could become President; I'm beginning to believe it.
~Clarence Darrow

Northern Spy said:

When I get home I'll take a look at my GM calculations. Mine was pretty snappy when relaunched and empty after repowering. After a few years of re provisioning (placing useless crap back in the lockers) her roll is more gentle.

Click to expand...

That is 180 degrees opposite of intact stability. A "too stable" vessel has a large GM and will roll quickly. Adding weight will lower G and unless there is a large change in draft, the GM will only increase and the boat will roll (snap)even faster.

I had also thought about putting some lead in the bilge (keel box) but I think she'd just get snappy again with the hard chines on my boat.

Click to expand...

That is the way it works. Adding weight down low increases static stability but increases roll rate. If you want a slower roll, take weight out of the bilges or add it higher.

Rick B- Well, in our case the boat is not 'Stiff', it rolls. A round bottom boat will roll, wood or plastic. Enjoy your comment as it relates to CG. Rolling was not the root cause of our original post yet is somewhat related.
I suspect that the designer, Ed Monk, a renown marine designer, configured the boat as close to CG rules as possible. As nothing of any magnitude, such as weight at a higher location on board, it could be as LL posted, a case of 2/1 length/beam results in a 'hobby horse' 'barrel rolling' trawler- resulting in recognizing that a pocket trawler is limited.
Ultimately, there is nothing so troubling that will result in not enjoying messing around in the boat!
Regards,
A.M.Johnson-ketchikan

Al said:

I suspect that the designer, Ed Monk, a renown marine designer, configured the boat as close to CG rules as possible.

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There are no CG rules for stability for uninspected recreational boats under 65 feet in length. There are capacity rules for boats under 20 feet but the CG could care less if a boat is stable or not unless it is an inspected vessel or is not in compliance with the power and loading limits of very small boats.

...it could be as LL posted, a case of 2/1 length/beam results in a 'hobby horse' 'barrel rolling' trawler ...

Click to expand...

A 2:1 boat has higher initial stability than a long and lean vessel of the same draft.

The ratio itself isn't the problem, it is more related to the length of the waves the boat operates in. A short boat is closer to the length of the wave and of course it will pitch more as it won't bridge several waves ... put a 800 foot long containership in a long Pacific swell and it will pitch like a horse as well. Ever see a film of a destroyer in a storm? Those ships are around 10 or 12:1.

Boatgm said:

I agree with doing some testing, both roll period and incline.

Click to expand...

Here, preparing for some kind of test.

CG= Center of Gravity,

AMJ

Home for the day, re-read Rick B post and want to make note of agreeing with the description of beam length offering.

In past local discussions of water conditions and our local fleet. The waters of S.E Alaska inside waters, offer a lot of 2 foot seas and the length of the troth is best crested with a boat in the 38-48 foot length as the boat will span two waves. Not so with our 27 foot boat, Rick is correct, we waller, rock and roll with each following swell. So Rick is correct as it applies to our local waters. Perhaps that explains that our commercial West Coast trollers U.S. and Canada, fall into that length class.
anyway, just wanted to make note and agree.
A.M.Johnson-Ketchikan