Foam blocks in weird areas

[BOAT]

I saw the permenant ballast at the factory - there were five of them all lined up in the first bay of the layup section. I wanted to see it so Mike pointed it out. They are like rectagles about 4 or 5 feet long and about 2 feet wide and they have a big slot in the middle in the shape of a daggerboard. They have rounded 'horns' at each corner. they are all rounded edges - gray and looked like lead - they looked like somthing that came out of a lead mold but could have just as well been some other material. It was very heavy - I tried to move one of them and I could not budge it one spec. I tried to just spin one and it was like trying to push a concrete wall - nothing - I could not move it. I don't know what it was made out of but is was very smooth all over and rounded all around. No shart edges. Not real sure how long they are but it seemed like at least 4 feet. Could be less.

here is a picture of what I "think" I saw - but it's like a UFO sighting - your never really sure what you saw:

[Crikey]

Yes, keep the flotation - and by the way, bring a rifle!

[Tomfoolery]

Yes, keep the flotation - and by the way, bring a rifle!

Reminds me of Captain Jack Sparrow riding the mast of his sinking ship into port.

[Herschel]

I was curious if the factory installed flotation on my 26X was designed to keep the boat with a 50HP engine afloat, so I called the factory several years ago, and they assured me that the weight of the engine had been figured into the flotation system. After several shipments of frozen steaks and a couple ones of meds that needed to be kept cool, I found I had four really nice heavy duty Styrofoam coolers sitting in my garage. I taped them shut and put them in the stern berth all the way aft where I just had empty space. They give me some comfort that I have a little margin for error. Like previous threads, I would rather be clinging to something floating that adrift in a PFD. It is all about doing what you can do, so, if something bad does happen, at least you aren't left saying "I wish I had..." My own thoughts are that when you consistently plan (reasonably, of course) for the unanticipated, over a lifetime, the chances one of those efforts will pay off big time are pretty good. Or, perhaps for one of your kids, who have learned from watching you.

[DanInCanton]

I always thought that, if worse came to worse, I would inflate my dingy inside the cabin. Even only half full of air, it should provide several hundred pounds of lift to augment the foam already installed. Of course, if I was wrong about that, I've lost my life raft .

[seahouse]

BOAT – interesting - based on your description, and given the cost difference between lead and concrete, my vote now is that the fixed ballast is likely concrete. And the daggerboard trunk might not be as robust as I previously thought (depending on how they fixed it to the hull), because the ballast was clearly not “cast in place”. The area feels absolutely solid whan you rap on it.

Note that any floatation located below the gunwale line has to be secured or somewhat fixed to be totally effective. Otherwise it will simply float around inside the cabin, wasting space, unless it's large enough to wedge against the ceiling. Then you want to hope it does that in the centre and not the sides, where it will cause instability and tipping, particularly in an X. In the Mac demo video you can see that the waterline when swamped with six souls aboard is just below the gunwale in the M.

I have no idea how any of this would translate to other Mac models, but the dingy sounds like an option I'd have on mind too, Dan. Do you know how much fixed ballast you have? In the past I've also thought about (not on my present boat of course) inflating car inner tubes inside little used, or inaccessible spaces.

- Brian.

Hmmm. So I wonder what the bags of sand are for in boat manufacturing? Casting?

[vizwhiz]

Note that any floatation located below the gunwale line has to be secured or somewhat fixed to be totally effective. Otherwise it will simply float around inside the cabin, wasting space, unless it's large enough to wedge against the ceiling.

While I agree with the technicality, I feel that this is misleading, because if the boat is swamped and full, then anything that floats inside the cabin WILL be wedged against the ceiling, or else the opposite..the cabin isn't full of water...is true, and not having the cabin full is actually not a bad thing in the scenario we're talking about...right? I mean, that indicates that the boat hasn't sunk... Of course, stuff could float out of the companionway and eventually leave it without the additional flotation, but that's getting a little detailed in light of the general topic.
I think the whole "airbag" in the boat idea is not really all that bad either, except that they would have to stay full (not like car airbags that deflate after you hit them)...but that idea would work pretty well, actually, on our boats, light as they are (compared to a heavy keelboat). The only safety factor you'd have to keep in mind is making sure nobody is in the boat still when inflating whatever you're using...so as not to trap them inside. It would be interesting to know just how much one of our boats weighs when swamped, meaning how much flotation is needed to keep it from sinking...it would be a shame to go through the effort of adding a flotation system and then have it not be quite enough...

[DanInCanton]

I have no idea how any of this would translate to other Mac models, but the dingy sounds like an option I'd have on mind too, Dan. Do you know how much fixed ballast you have? In the past I've also thought about (not on my present boat of course) inflating car inner tubes inside little used, or inaccessible spaces.

As far as I know, the total fixed ballast in my 25 is the 650-pound iron centerboard. I imagine that a dingy rated at 600 pound safe carry capacity can probably displace much more weight than that as a floatation aid. Even partially inflated, I assume that the dingy alone could carry the centerboard and the cubic yard or two of foam floatation onboard could easily handle the boat and all my gear (keeping in mind that fiberglass displaces less than half of its dry weight in the water). But you know what happens when you ass-u-me . Of course, this also assumes that I would have time to inflate the thing before I was treading water, so I believe the best course of action is not to sink in the first place.

A few years ago, I experimented with empty 2-litre soda bottles. With the temperature extremes in Ohio, the bottles with just the tops screwed back on had deflated to about half their original size within just a year. However, bottles that I shot a little bit of expanding foam into the mouth of before I put the cap on have stayed fully inflated to this day. If you're a soda fiend like me, this might be your best floatation value...just be sure you have a lot of bottles ready before you pop the seal on your expanding foam--one can sealed about twenty bottles and that stuff doesn't stay good very long after you use it for the first time.

Dan

[grady]

I always thought that, if worse came to worse, I would inflate my dingy inside the cabin. Even only half full of air, it should provide several hundred pounds of lift to augment the foam already installed. Of course, if I was wrong about that, I've lost my life raft .

if you actually were sinking I think it would be best to inflate the dingy outside the Mac, paddle, oar, or motor to shore and call the insurance company.

[Russ]

Has anyone heard of a case of a Mac getting full of water, either by a hole or otherwise (except Steph's daggerboard post)? I haven't. These boats have no thru-hull fittings to leak, no shaft logs or rudder posts. You can lay it down on it's side and it still won't fill with water. Just how does one get a Mac full of water? Nice to have the insurance of flotation, but how often does it get called into play?


Yea, I'd keep the inflatable dinghy to keep me dry if that day ever happened. Much more versatile.


--Russ

[DanInCanton]

It all depends on the size of the shark circling the boat .

[seahouse]

While I agree with the technicality, I feel that this is misleading...

I don't think it was misleading, Viz. I mentioned it applied to an M (or X which was in the OP's question), and the photo on page one of the thread shows the water level at or around the gunwale, which leaves plenty of space for things to float around inside without being wedged (or even touching in some cases) against the ceiling. But sure, it's possible the water level could go even higher than that in waves and with heavy loading, though. That may or may not apply to other models of Macs, though. No such warranty either expressed or implied!

And in order to provide maximum buoyancy an object must be pushed under the water level, so the water level really has to be right at the ceiling for any free-floating object to provide its maximum buoyancy.

If I were to install airbags on a boat, I would install them around the perimeter (port and starboard), where they could add stability in a swamping, have no risk of trapping anyone inside the cabin, and be routinely inflated as a built-in fender for docking.

Hey Dan – inflate your pop bottles on the coldest day of the year, if you can judge when that is, and your empty bottles will be fully inflated all year 'round. Seems to me they could do for short-term makeshift fenders at the dock too. I've made beer in them too– with a rubber valve in the top to stop them from exploding, but even without it they can take a lot of pressure before that happens.

- Brian.

[Catigale]

The ballast on the is described in the lit as resin, not concrete.

As far as I know, the total fixed ballast in my 25 is the 650-pound iron centerboard. I imagine that a dingy rated at 600 pound safe carry capacity can probably displace much more weight than that as a floatation aid

The rated capacity of the dinghy refers to it operating in non-swamped mode, so it would not offset a 650lb ballast once it was filled with water.

[kadet]

The ballast on the is described in the lit as resin, not concrete.

When I was researching mine before I purchased the factory blurb said one of the differences between the and was 300 pounds of permanent ballast being a mixture or resin and sand.

Epoxy Concrete may be

[seahouse]

So its back to a resin ballast, and that explains the sand on the product list. I don't recall seeing that in the product literature, but that might explain where that thought came from in my head - the sales literature subliminally seduced me!

For production efficiency it would make sense that the ballast blocks are cast separately ahead of time, then set in place in the hull around the trunk within another bed of resin.

-B.