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Archive for Outboard Flipped Into Boat

The Leash, a tether for large outboard motors, entered the market in early 2016. They especially focus on preventing bass boat outboard motors from entering the boat after striking a floating, submerged, or fixed object.

Their patent application was filed 22 December 2015 and published 18 months later on 22 June 2017 by the U.S. Patent Office as Publication Number US2017/0174303 A1.

Roy John Grohler of Kentucky is the inventor. The patent is assigned to The Leash Tether LLC. of Kentucky.

The Leash: left and right views side by side

The Leash: left and right views side by side

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In December 2013 we published a report, Approaches to Prevent Outboard Motors From Flipping Into Boats After Striking Floating or Submerged Objects in which we identified several ways to prevent outboard motors from breaking off and flipping into boats after striking submerged objects. One of those was was active trim control (see pages 33-34 of our report) by using a magnetic fluid in the trim (tilt) cylinder and using position feedback (how far is the rod extended) during a log strike to adjust how much resistance the cylinder is applying to the upward swinging of the outboard. While the impacts are not as severe, the same approach is used for shocks on several cars.

Magnetic fluids are sometimes called Magneto-Rheological (MR) fluids. Also sometimes spelled as magnetorheological fluids. They change viscosity based on the presence of a magnetic field and upon its intensity.

Active control brings the ability to respond faster than existing systems and limit pressure overshoot today’s relief valves. It also provides the opportunity to measure the magnitude of the collision as it is occurring and then select the best way to respond or possibly to select one of several preprogramed ways to respond. One program could allow the outboard to rise up over the object before maximum resistance is applied (called trailover).

MR fluids are also currently used in some high end, rough water vessel chairs to dampen vibrations (protect your back in very rough water) for the U.S. Navy.

In January 2015, Brunswick filed a patent on this active trim cylinder approach that includes some interesting comments.

Brunswick’s patent, U.S. Patent 9,290,252 was issued 22 March 2016.

Delph Magneride image we posted with our discussion of using MagnetoRheolopical fluids in trim systems in 2013.

Delph Magneride image PropellerSafety.com posted with our discussion of using MagnetoRheolopical fluids in trim systems in 2013.

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We have previously written extensively on log strike testing, the variables involved, and more specifically on trying to prevent outboard motors from breaking off and entering boats after striking floating or submerged objects.

This installment focuses purely on durability testing of prototype outboards. It does NOT address the issue of outboard motors breaking off and flipping into boats, the need to make sure production outboards maintain the same durability, production quality control issues, design changes, or other issues. It purely focuses on developing a test stand and a test protocol to test a single prototype outboard motor for durability in striking floating or submerged objects.

Note – the Asian outboard manufacturers tend to refer to log strike testing by the phrase, driftwood testing.

Note – Log strike testing is DANGEROUS, please read the DISCLAIMER at the bottom of this post.

This post is not meant as a “pick one” offering. It is more of buffet from which manufacturers new to log strike testing consider picking some things if they like them and bring some of their own ideas to the table as well to create something that works for them at the stage they are now in.

On Water Log Strike Testing

Most major outboard manufacturers now have a log strike test procedure in place for durability testing of outboard motors. Some still perform on water testing by running flat bottomed boats over floating logs.

Log strike testing news clip. Corpus Christie Caller-Times. 30 April 1960. Page 6D.

Log strike testing news clip. Corpus Christie Caller-Times. 30 April 1960. Page 6D.

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A college student in Sweden, Fredrik Helgesson, designed a test stand to log strike test outboard motors (outboard motors impact floating logs).

The report is titled, Konstruktion av “log strike”-testrigg for utomboardsmotorer.

Back in early 2016 Mr. Helgesson, a mechanical engineering student at Halmstad University in Sweden, contacted us a few times for technical specifications on how the industry tests log strike systems. He said he was working on a thesis focused on that topic. We supplied him several publicly available materials, some thoughts on the topic, and told him that if he was not teamed with one of the major outboard manufacturers he would likely not have access to the exact specifications manufacturers use for log strike testing.

A couple months ago we noticed his paper had been published by Halmstad University.

We then learned his project was more of a design project teamed with a manufacturer of diesel outboards, Cimco Marine AB.

Cimco Marine OXE diesel outboard

Cimco Marine OXE diesel outboard

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U.S. Coast Guard emblemThe U.S. Coast Guard National Boating Safety Advisory Council (NBSAC) will be holding its 97th meeting on March 23-25, 2017 in Arlington, Virginia.

Their March 2, 2018 notice in the Federal Register invited public comments, due by March 6th if they were to be distributed in advance to NBSAC members.

We submitted a pubic comment, our recent Propeller Safety dot com post on our updated design chart for preventing outboard motors from breaking off and flipping into boats when striking floating or submerged objects.

We used a cover letter to point out NBSACs own discovery of this problem as retold in the NBSAC95 minutes and attached a copy of our design chart post. Read More→

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U.S. Coast Guard emblemThe U.S. Coast Guard National Boating Safety Advisory Council met for its regularly scheduled NBSAC 95 meeting April 21-23, 2016 in Arlington, Virginia.

Minutes of that meeting were posted in October 2016.

We have spent considerable effort in recent years encouraging NBSAC to:

  1. Recognize outboard motors are breaking off and entering boats with their propellers still running after striking floating or submerged objects, and that this accident scenario is often associated with bass boats.
  2. Increase awareness level of this accident scenario

As we recently closely read the April 2016 NBSAC meeting minutes we noticed they did mention this accident scenario, but they described it in a manner we have never seen or heard before.
We find that quite odd, since several members of the committee and other industry representatives present were well associated with the problem.

NBSAC 95 minutes composite

NBSAC 95 minutes composite

The image above is a composite of pages 1,7, and 8 of the minutes. Read More→

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Back in July 2016, we posted a chart for use in designing and testing outboard motors in a way to prevent them from breaking off and entering boats when striking submerged objects.

Today we are posting an updated / enhanced version of that chart. The new chart specifically identifies three more potential design / testing paths to achieve the objective.

Flip In Design Chart

Flip In Design Chart


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We have been following the rising waters in California which the industry was first touting for the additional sales it would generate as many lakes had been down a while depressing marine sales there.

Now as waters continue to rise, California faced/faces continuing issues at the Lake Oroville Lake spillway evacuation, and now the United States Coast Guard is said to be planing to issue a debris warning for San Francisco Bay today.

ABC News 7 of San Francisco released a video when they learned of the debris warning planning to be issued Wednesday 15 February. They note much debris is still floating down into the bay from the Sacramento Delta.

We cover the hazards of marine drives striking floating debris on PropellerSafety.com including the possibility of outboard motors breaking off and flipping into boats while still under power when striking floating debris at speed.

We suspect high waters will increase debris in many California waters, especially impacting bass tournament fishing. We encourage everybody to be extra safe out there and lookout for debris.

We will post the debris warning when it is released.

Meanwhile, Pressure-Drop, a sailing forum, has some great satellite, aerial, and on water photos of the status of the region. The also have a nice discussion of flow rates at the bridges and how and why they differ at the surface near bridges.

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Outboard can strike submerged object, break off, and flip into the boat warning

Outboard can strike submerged object, break off, and flip into the boat warning

In 1970, William Haddon, Jr. a well known safety expert published a ground breaking safety article:
 
On The Escape of Tigers: an Ecological Note.
by William Haddon, Jr.
American Journal of Public Health.
December 1970. Vol.60. No.12. Pages 2229-2234.

The the article has since been widely republished and reprinted.

The thesis of the article is that per Mr. Haddon, by 1970 The United States and most developed nations had made significant progress against “living environmental hazards” (medical issues caused by living organisms such as germs, bacteria, etc.). However, similar progress had not been made against “non-living hazards” (accidents leading to injury or death).

The field of Medicine had many strategies and processes by which to attack emerging problems causes by living organisms (such as the Zika virus in current times). While science may not immediately defeat the Zika virus, the basic processes and methods to use to begin to develop a means to combat such a threat are well known.

That same basic structure of processes by which to develop a means to combat an emerging health risk caused by a living organism did not exist to combat a health risk caused by a non-living structure (such as some new type of accident that injures or kills humans).

In his paper, Haddon tried to bring structure to the process of mitigating or eliminating accidents resulting from the sudden release of energy.

In order to better marshal resources against these “non-living hazards”, William Haddon, Jr. suggested that many of them result from “the transfer of energy in such ways and amounts,and at such rapid rates, that inanimate or animate structures are damaged. (Like a bass boat outboard motor striking a submerged object, breaking off, flipping into the boat, and striking those on board with its still rotating propeller). Haddon goes on identify some harmful “non-living hazards” that interact with people and property as: hurricanes, earthquakes, projectiles (like an outboard motor), moving vehicles (like a boat), ionizing radiation, lightning, conflagrations, and notes the cuts and bruises of daily life illustrate our interaction with the rapid transfer of energy.

The paper’s title derives from one example of the quick release energy, the release of tigers. Read More→

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Rex Chambers' boat with outboard motor broke off

Pro angler, Rex Chambers’ boat with outboard motor broke off

When outboard motors strike submerged objects they can break off and flip into the boat as seen in our lists of outboard motors breaking off and flipping into boats and large outboard motors breaking off and flipping into bass boats.

We previously posted information on several existing and proposed solutions, including The Leash, a vectran tether targeting bass boat applications.

Submerged objects have a wide range of characteristics ranging from almost pure water with just a few weeds or small pieces of debris all the way up to stumps, pilings, dredge pipes, railroad ties, and concrete piers. When outboard motors from various manufacturers of various sizes and speeds strike this wide range of objects, the outboard motor log strike system behaves in a number of different ways (modes).

Especially of interest are outboard motors that break off the boat. Breaking off the boat is a prerequisite to breaking off and flipping into the boat. Not all outboards that break off will flip into the boat. But for an outboard to pass over the rear deck, and enter the seating area of a bass boat, it must first break off the boat.

The Outboard Motor Log Strike Modes Chart for a bass boat below illustrates the range of behaviors (modes) encountered.

Outboard Motor Log Strike Modes

Outboard Motor Log Strike Modes

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