Re: [omc-boats] Re: omc-boats-digest V1 #367

I've had two Rogues neither of which had any additional flotation above the floor.
  ----- Original Message -----
  From: lib1@...
  To: omc-boats@...
  Sent: Wednesday, August 24, 2005 9:21 PM
  Subject: Re: [omc-boats] Re: omc-boats-digest V1 #367

  Phil,

  That's really an interesting post, thanks for sharing it with the group. We had a 1960 Larson All-American. It's double floor was an air cavity and it had a clear inspection cover to check for water or moisture trapped inside, but the side gunwales had foam blocks, as did the underside of the fore deck. In other words they keep the foam up, so it was harder to get it water logged. Never swamped it, so don't know how well it worked. I think the OMC engineers were probably inspired/influenced by the 1958 "unsinkable" Boston Whaler.

  It got me thinking how much cubic volume is beneath the floor (filled with foam) on our Evinrudes & Johnsons?

  So here's some interesting (or maybe boring) facts, I've gleaned from the original 65-66 boat brochures:

  The Evinrude 16 Outboard specs claimed: "25 cu ft polyurethane foam sufficient to float maximum recommended passenger load, motor, and gear."

  I believe on the outboard models and on the 90 hp sterndrive all 25 cu ft of foam is in the cavity under the floor.
  If we do the math: Hull weight: 900 lbs, motor weight for V4 90-100 hp: 400 lbs; max load capacity: 1400 lbs so that adds up to 2700 lbs.
  So now if we divide 2700 lbs by 25 cu ft each cu ft is supporting 108 lbs on the Sweet/Sport 16 Outboards.

  Wonder how the sterndrives compare, as they would seemingly tend to be more stern heavy than their outboard sisters?

  On the 120 and 155 hp stern drives OMC engineers added an additional 4 cu ft of foam, above floor, with (2) 2 cu ft blocks on either side of the engine compartment.
  (From Ralph L's article, this was probably done to help keep the boat more level when swamped, as the heavier sterndrive would most likely go bow up when swamped)

  The 120 Chevy 4 added about 260 lbs over the V4 90 and the V6 Buick added 375 over the 90 sterndrive. The max load capacity didn't change.
  Thus the sterndrives with max load, gear, fuel weighed in at: 90: 1450+1400 = 2850; 120: 1710+1400 = 3110; & the 155: 1825+1400 = 3225
  90 foam supported 2850/25 = 114 lbs/cu ft 120 foam supported 3110/29 = 107 lbs/cu ft and the 155 foam supported 111 lbs.

  for comparison the 14' Playmate (90 hp sterndrive) had 18 cu ft/foam; weighed 1180 lbs and supported 950 lbs max load; (1180 +950)/18 = 118 lbs/cu ft
  and the 66 19' Rogue (200 hp V8) had 35 cu ft foam; weighed 2115 lbs and supported 2000 lbs max load; (2115 + 2000)/35 = 117 lbs/cu ft.

  Another curious fact, as the advertised weights for all models went up slightly in 67, 68, 69-70, the load capacities and foam specs did not change, which tells me the margins for safety were conservatively designed from the get go.

  Does anyone know if the Rogue or Playmate used the additional above-floor floatation?

  For those of you that re-foamed a 16 ft hull, does the 25 cu ft of foam sound about right?

  Lee Shuster

  ----- Original Message -----
  From: "Phil Budne" <phil@...>
  To: <omc-boats@...>
  Sent: Wednesday, August 24, 2005 5:34 PM
  Subject: Re: [omc-boats] Re: omc-boats-digest V1 #367

> Lee wrote:
>> Last night I sent some scans (which apparently are too large for the mail
>> list server) of the original Evinrude construction process.
>
> I found one of them, and have added it to the "lit" page.
>
>> Here's what the paragraph said of the original construction and foaming
>> process:
>>
>> "Rigid, closed-cell polyurethane floatation (equivalent to 73 life
>> preservers) provides additional structual strength. Foaming is done under
>> 250,000 lbs of pressure. Closed dies lock the hull in a steel embrace during
>> the foaming operation."
>>
>> "Special foaming machines produce high-pressure foam twice as dense and far
>> stronger than poured-in foam. It can't "work" or develop voids; won't absorb
>> moisture, shrink. or pull away from the hull regardless of temperature or
>> operating conditions."
>>
>> If you do the simple math that one live preserver could support an adult
>> weighing 170 pounds x 73 then that equals roughly 12,410 lbs of floatation.
>>
>> I think Evinrude was more than meeting the floatation standards of BIA or
>> whoever it was reasponsible for setting such standards..
>
> One of the main innovations Ralph Lambrecht (head of the OMC Boat
> Division, and a co-designer of the OMC/Johnson 17 hull) wrote about in
> his "40th anniversary of the OMC 17 -- a benchmark in boatbuilding
> standards" article, published in the July 2003 issue of "Boat & Motor
> Dealer" was the flotation;
>
> Not just convenicnces, but safety too
>
> Between the flat interior floor and the bottom were two
> fiberglass hat-section stringers with alumninum plates molded
> in for the engin mounts, of which there were only two on the
> floor for th two-cycle V-4 sterndrive. The upper mounts were
> bolted to an aluminum beam running across the inside of the
> transom. The stringers were filled with high-density urethane
> form, as were all the empty spaces between the floor and the
> bottom. Plenty of room was left under the engine, making it
> easy to keep clean. The bilge-pump/blower-unit was mounted in
> a sump molded into the floor panel. If the water level ever
> got high enough to submerge the entire unit, both the pump
> and the blower on top of the sealed electric-motor housing
> would pump water out of the boat.
>
> The high-density foram in the bottom was mainly for support,
> but it also made the boat unsinkable. One of the side
> benefits of the OMC 17's unique bottom design was that it
> placed a large ammount of foam out in the sponsons on either
> side forward. And the deepest part of the foam near the stern
> between the stringers, giving the boat three-point boyancy.
> The result was that the OMC 17 floated level and upright when
> swamped. In fact, every boat that OMC designed in built in
> the 8 years they were in the boatbuilding business had this
> capability.
>
> You could also leave the drain plug out of your OMC 17 and
> stay on board, because there was no place for water to go
> under the floor. In fact all five 170-pound people the boat
> had seats for could stay in the boat with the plug out, and it
> still floated with the hull-to-deck molding out of the water.
> This was a safety feature worth talking about. Virtually all
> fiberglass boats built in the early 1960's sank when swamped,
> or loaded with only their bows out of the water.
>
> Changing the Industry
>
> The OMC 17's remarkable floatation characteristics came to the
> attention of the American Boat and Yacht Council, and what was
> to become it's Hull Performance Project Technical Committee.
> In the early 1970's more than 1,700 people were dying each
> year in boat accidents -- mostly in boats less than 20 feet
> long. Clearly, the OMC 17 offered some promising solutions to
> this trend. One result of the committee's investigation was
> the enactment of the "ABYC" Standard H-8 for outboard boats
> under 20 feet in length," which required that all such boats
> float level and upright when swamped with their rated
> passenger load centrally located on board.
>
> This meant that passengers in a flooded boat would only get
> wet up to their waists if the didn't panic and they were not
> out in big waves. Such boats would also be stable when
> inverted, providing a large, unsinkable, and highly visible
> object to hang on to. Major boat manufacturers began to
> follow the standard voluntarily.
>
> Also in the early 1970'sthe Boating Safety Act was enacted,
> empowering the Coast Guard to establish regulations for
> recreational boatsq aimed at reducing the rate of boating
> fatalities and injuries. The causes of these accidents were
> analyzed, and it became apparent that the greatest reduction
> could be made by doing two things: increasing the availibility
> and use of personal floation devices, and making it possible
> for the passengers to stay with the boat, whatever condition
> it may be in. The level-flotation requirements of the ABYC
> standard were among the first federal safety regulations,
> along with a requirement that a PFD be carried on board for
> every passenger.
>
> These requirements addressed the causes of more than
> two-thirds of the boating fatalities, and were futher targeted
> for outboard-powered boats less than 20 feet in length -- the
> boats most frequently involved in fatal accidents. The rules
> were somewhat relaxed, though, for inboard boats, due to the
> difficulty of keeping a boat's stern afloat with an 800-pound
> engine located there. Inboard boats were required to only
> have "basic floatation," meaning that the vessel would have to
> stay afloat, but not neccessarily as a stable and level
> platform. At the same time, federal regulations also enacted
> standards for the fuel and electrical systems, ignition
> protection of electrical components in gasoline engine and
> fuel-tank spaeces, positive compartment ventilation and so on.
>
> Thirty years after the regulatory process was initiated, annual
> boating fatalities in the United States have declined from more
> than 1,700 to about 700.
>
> While it may be a stretch to give OMC all the credit for
> establishing these manufacturing standards, it's clear that
> they led the way. Someone had to show that it could be done.
> OMC produced more than 6,000 boats a year -- mostly inboards
> -- in the late 1960's and each one of them had level and
> upright floatation. The OMC 17 was the first of that line,
> and as such, it deserves our recognition.
>
> (hmm, only the first two columns, and I will have typed the entire
> article!)
>
> phil
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Received on Wednesday, 24 August 2005