Securing an engine in a rollover

[Jim Cate]

Re strength loss at engine room temps:

From your links, you quote a loss of ~50% at 100 C. I think that is satisfactory, in that Matt's engine room temps are likely less than 100 C (mine surely are) and if one used even 4 mm Dyneema 75 there should be adequate strength to suspend the engine.

But as you say, if worried about this, reverting to steel cable is certainly a valid option, and has worked for many.

And the through bolt method, if applicable to Matt's mount design, is strong and tidy. Would likely require removing the mounts for drilling... much more effort than simply wrapping a soft shackle around it.

Jim

[Steadman Uhlich]

Originally Posted by Neptune's Gear

I use Dyneema Loops...

I am curious to see these in use. Would you please post a photo in this thread?

[UNCIVILIZED]

Jim,
The key bit to me is that per Honeywell, the advised max. long service temperature for the stuff is 70 degrees Centigrade (158 degrees F) on page-4 of their Data Sheet, under "Thermal Properties" http://www.honeywell-advancedfibersa...ide&download=1

Though, yes, odds are, with a call to Honeywell, & a couple of the other makers of said fiber, the question could be haggled out.
Although to do it properly, would really require some semi-extensive temperature readings over time, & various operating conditions in the specific engine compartment in question.
Some have great ventilation, others adequate, & some virtually nil. Plus, there are of course huge differences in terms of how much thermal & sound insulation in different compartments. Ditto on the R-value of what their shells are made of.

Bottom line, I'm just saying, that given the choice, for me, Spectra/Dyneema wouldn't be my selection for such a chore is all. And I'm just trying to provide what I know, information wise, on the materials, as was asked for.


One other type of line, & or line cover which folks may run across, that @ the outset, looks viable, is PBO (aka Pobon, or Zylon). It's used (heavily encased) as standing rigging in a few apps. However, while it's great in terms of strength to weight, & tolerable in terms of heat resistance, it breaks down in any kind of light. Even light bulb light. Just so you're forewarned.

I used to see it commonly listed/carried as a heat resistant line jacket, but perhaps it's fallen out of favor? I say as much given that, for a while, it was used as sail material in a few of the high end one design fleets. But even with storing the sails in light proof boxes in between races, it got a bit pricey for the guys with bottomless pockets... or so it would seem.

[GILow]

Originally Posted by Neptune's Gear

GILow, my engine is the same as yours, VP2003T. ...

Matt, that engine comes up in my Google search as a 250Kg 43HP Turbo 3 cyliner Volvo. Is that right? If so, very different to the monster I am trying to contain, at least in weight.

Not saying your solution does not apply, far from it, but just curious about which engine you are fastening down.

My engine, being a converted truck engine, had no special mounts for marine use, anything I did was going to be a custom conversion. For better or worse, I chose mounts that were not particularly rollover-proof, so I am now, belatedly, addressing the issue.

Matt

[GILow]

Originally Posted by Jim Cate

Would likely require removing the mounts for drilling... much more effort than simply wrapping a soft shackle around it.
Jim

Jim, this is a bit of a sensative subject at home right now. I had to drill 30 holes in total to make the new mounts, all with my faithful 40 year old drill press. That's 30 holes in 12mm plate, most of them 13mm or 19mm holes, so a fair bit of swarth.

Well, this morning my son fished the third bit of swarth out of his socks before going to school, and my wife gave me one of those looks that happily married men learn to take seriously. (I didn't admit that my shoes were troubling me at the office yesterday, and on inspection I pulled two nice long lengths of swarth out of my socks too.)

So, removing the mounts to drill them again, while a very simple process in itself, has some ramifications for home tranquility that would be ignored at my peril. I could sneak the press down to the boat, but I suspect the club would frown at the sight of me staggering down the pontoons with a 200kg drill press.

As it is, I have been instructed to vaccuum the back garden. I will do so, I know the value of a happy wife.

Matt

[UNCIVILIZED]

Not to start a ruckus over the topic, but a few tips & thoughts for some of us with less of an engineering or education by sailing background. And to look a touch further into some Engine Room realities.

Regardless of whether you use steel cable, chain, or soft line as your safety system, a ballpark minimum safety figure for each line or chain, is 5x total load (after allowing for material breakdown due to conditions, for say, welding on certain metals, & especially on Dyneema where the industry safety standard's actually a lot more [see synthetic rigging]). And I'm thinking on 4+ attachment points, even with this safety factor.

The number's more or less a general standard. Or so I've come to understand it.
Also, with Dyneema (I don't recall the percentage for wire) it's not recommended to plan on loading it past 20-25% of it's breaking strength (again, after allowing for degradation, splices, sharp turns etc.)

Also, it'd be preferable to use thimbles (again, especially on soft lines) where the lines are attached to anything other than a well radiused & smoothed metal attachment point. And often enough, even then I'd want'em (even for wire), especially given the app.
I mean you put them in standing rigging right? As well as some of the more heavily loaded running rigging fittings.

Given that Dyneema (or any other line) will be spliced, or tied, there needs to be some accounting taken due to this weakening the line to some degree.
Ditto due to it's taking sharp turns (this includes wire too), as in the above listed points. Allowable radii for such are posted in most line & rigging catalogs.

- The reasoning for the safety factors up top, & that I'm mentioning: At a minimum, think about the shock load of an engine falling onto said lines, & trying to break free during a roll over (these lines don't have any give at all). Plus, at any point in time, it's not hard to see 75% of the load being slammed onto just one of the 4 safety lines.
Think on a boom which has 3 blocks as part of it's sheeting system, when one gybes, typically one or two of them takes the vast majority of the load... it's not an even distribution, generally.

If that isn't enough, then there's the bit about the lines/cables attempting to keep said monster in place throughout the full length of a storm which produced conditions severe enough to make you do a 180 to begin with (and perhaps a few more yet). All while them rubbing & chafing on all manner of things never foreseen nor intended. Likely some of them "fairly warm", depending on where they are. Or where various parts & bits were/became detached from, & or leaked out of.
Ever get hot engine oil, or coolant on your hand?

Plus, in line with the Devil's Advocate theme. Some engine ventilation systems have automatic blowers... which we may not notice if they fail to come on every time. Albeit, a hugh number/percentage of such systems are manually operated.
Plus, on any which are automatic, I've seen few which come with a built in timer to make them automatically run for X number of minutes, post engine shut down, in order to fully cool the space.
Nor are any type failsafe vs. a bird starting to build a nest in a piece of duct work, or Dorade Box.

[deblen]

Chevrolet Motor Mounts | The Center for Auto Safety RECALL NOTICE

Okay-showing my age here.
I drag raced in '60s & early '70s.
We used motor mount restraints,because the torque transmitted from 7lb pressure MT racing slicks,transmitted thru the drive train to the engine,when I dropped the clutch,at 5600 RPM (standing start) , caused or could cause the front left motor mount to rip apart.
This allowed the engine to rotate & jam various linkages-notably the throttle.
Marine diesel mounts are specified by eng. mfgr to handle that particular eng.-HP,Torque,weight,etc.,so it doesn't matter much your HP,when you fetch the eng. to a quick stop,by snagging a pot warp,etc.
Marine diesel mounts are designed,primarily,to stop noise & vibration from annoying the passengers.The more flex-the better in that regard.Not all were designed with rollover/engine restraint in mind,as evidenced by VP 2000 series like mine.
Since the little 3cyl bugger shakes like hell @ idle,I was reluctant to replace the mounts with a more modern design,such as R & D.
I did inst. chain restraints as previously described,mainly to limit travel/stretch of replaced mounts,for longer life.
Has anyone replaced their VP 2000 mounts with a suitable substitute,did you notice any diff.in noise/vibe. on your boat,& what brand/model did you use?
Tks / Len

[sanibel sailor]

Originally Posted by GILow

But it begs the obvious question. What sort of boat does a person who plays with 800HP cars sail?

Matt

A Bristol 35.5 among others

[UNCIVILIZED]

Originally Posted by deblen

Okay-showing my age here.
I drag raced in '60s & early '70s.
We used motor mount restraints,because the torque transmitted from 7lb pressure MT racing slicks,transmitted thru the drive train to the engine,when I dropped the clutch,at 5600 RPM (standing start) , caused or could cause the front left motor mount to rip apart.
This allowed the engine to rotate & jam various linkages-notably the throttle.

I did inst. chain restraints as previously described,mainly to limit travel/stretch of replaced mounts,for longer life.

Len, you're not showing your age overly much via the above. When I was really starting to get into cars (a few years after being legally able to drive), say 2 decades back, these mods were common. The piece of chain welded to the frame to stop the over twisting thing I mean.
And honestly, it was the first solution which went through my head when some of the details of the problems guys were having/trying to prevent, came to light in this thread.

[banjoship]

Matt, I am not sure which mounts you ended up using.

On Banjo I have PolyFlex mounts. On their site, they state "They are designed to have a failsafe that in the event of a capsize the engine will not break away from it's bearers."

See Home - Poly Flex Group - Advanced Polymer Technology for Vibration Control

I clarified this point with PolyFlex, mentioning dynamic loads, before installing new mounts with my engine replacement. The old engine was also on PolyFlex mounts.

Perhaps you should check with your mount supplier?

Lee

[GILow]

Lee,

I wanted Polyflex. And I was going to buy them, right up to the point where the price doubled because I was over the magical weight limit for the set I was considering. Yep, doubled, to around $240 per mount. Eeek!

So I bought some vastly inferior cheaper mounts made by another manufacturer (OK, yeah, I am being evasive here, maybe just a little embarrased).

But, I will say, no matter which mounts I bought, I was always going to want a safety backup in the event of a roll over, so I am no worse off in that regard. The real question will be how well the inferior cheaper mounts last compared to the Polyflex, which have a great reputation.

I do have a polyflex coupling for the drive shaft though.

Matt

[GarthGregory]

I would use 4 x s/steel wire rope x 10 mm dia. and crimped / swaged at each end of the rope , so that one end could be bolted to the top of the engine mount and the other end bolted to a substantial stringer in the hull . As short a s/steel cable as possible , but one that allows a little flex , so as not to transmit any vibration .
cheers G.

[GordMay]

A very interesting article from Yachting Monthly magazine:
Crash Test Boat – Capsize
What really happens during a capsize? How can we make the saloon safer?
Read more at ➥ Crash Test Boat - Capsize

[GILow]

Originally Posted by GarthGregory

I would use 4 x s/steel wire rope x 10 mm dia. and crimped / swaged at each end of the rope , so that one end could be bolted to the top of the engine mount and the other end bolted to a substantial stringer in the hull . As short a s/steel cable as possible , but one that allows a little flex , so as not to transmit any vibration .

cheers G.

This certainly appeals as a good simple solution.

Matt


Sent from my iPad using Cruisers Sailing Forum

[JPA Cate]

Matt,

FWIW, Jim and I were talking about this, and he said that the soft shackles would be so strong that only one of them could easily support the weight of the whole engine, so four of them would be just super-strong. Since your rebuild, there should not be so much heat as to be anywhere near damaging the Dyneema, and I would expect the area will stay pretty clean.

Ann