Ike
Senior Member
- Joined
- Apr 7, 2006
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I have been involved with the prop guard issue since the 1980's. The USCG has been researching it and dealing with both the advocates and the opponents for longer than that. In the mid 80's I was the project manager on one of the USCG research projects on prop guards. I also held public hearings in Florida and Maine in the late 80's on this subject. So over almost thirty years I have definitely formed some opinions about their effectiveness.
At speeds up to about 10 knots prop guards can be an effective way to prevent catastrophic prop strike injuries. At speeds much above that and beyond they are not. Being struck by a boat, a skeg, or any underwater part of a boat will cause traumatic injuries especially to the head. This has been demonstrated through actual tests using dummies (no humans were used, no matter how dumb they are. )
Prop guards do have their place but they are not the only answer.
The first is operator education. Never run the engine when you have people in the water. Maneuver to pick them up then shut off the engine.
If people are swimming off your boat, anchor and shut off the engine.
Operators need to tell people on their boat about the dangers of an exposed propeller.
Operators need to know where everyone is and what they are doing when getting the boat underway. (there was a particularly grisly case where a very intoxicated young male dove off the swim platform on a houseboat just as the operator started to back down. I was one of those who had to deal with his mother. It was not pleasant.)
Swim areas need to be better marked and boat operators need to know where they are and stay away from them. This not only applies to boats with props, but jet boats as well.
Jets are an alternative solution but only at low speeds. At planing speeds they still present a hazard to anyone hit.
Other devices such as kill switches that shut off the engine when someone falls overboard, or interlocks when the boarding ladder is lowered may be more effective. There are also various alarms that can be had to warn about people in the water, or if the boat is backing.
Prop guards do affect top end and fuel consumption on planing hull boats. They also affect maneuverability, but how much depends on the type of prop guard.
Not all prop guards are created equal. Different types have different characteristics. The type you use depends on what you are trying to do. Some are designed only to keep weeds and debris out of the prop. Others are designed to prevent people from getting body parts in the prop. So the prop guard has be chosen for it's function.
There are significant differences between prop guards and nozzles designed to improve the efficiency of the propeller. The two should not be confused. They do two completely different functions.
Believe it or not research has been (and probably still is) done on ways to detect people in the water by a speeding boat, and immediately stop the prop. Unfortunately this doesn't work very well. Nothing useful has come out of it yet. Forwarding Looking Sonar simple doesn't give enough warning time, not even for rocks and logs and such that present much better targets than humans., except at very low speeds.
Last but not least by any means, the market. On the whole, boat owners simply don't want them. Prop guards have been available as an option from most outboard manufacturers for over 30 years. Some boat manufacturers offer them too. There are a variety of prop guards available on the aftermarket. Hardly anyone buys them. Why this is, who knows. Perhaps most boat owners don't know they are available. The engine makers aren't pushing them either. But my sincere opinion is most people don't want them until something catastrophic happens.
Prop strikes are not rare. They are a small number of the total accidents. In 2010 out of 4604 reported accidents there were 49 struck by propeller accidents and 31 struck by vessel accidents. 1 of those was a fatality. But unfortunately when they do they are almost always catastrophic for the injured person resulting in permanent disabilities and life long need for medical care.
At speeds up to about 10 knots prop guards can be an effective way to prevent catastrophic prop strike injuries. At speeds much above that and beyond they are not. Being struck by a boat, a skeg, or any underwater part of a boat will cause traumatic injuries especially to the head. This has been demonstrated through actual tests using dummies (no humans were used, no matter how dumb they are. )
Prop guards do have their place but they are not the only answer.
The first is operator education. Never run the engine when you have people in the water. Maneuver to pick them up then shut off the engine.
If people are swimming off your boat, anchor and shut off the engine.
Operators need to tell people on their boat about the dangers of an exposed propeller.
Operators need to know where everyone is and what they are doing when getting the boat underway. (there was a particularly grisly case where a very intoxicated young male dove off the swim platform on a houseboat just as the operator started to back down. I was one of those who had to deal with his mother. It was not pleasant.)
Swim areas need to be better marked and boat operators need to know where they are and stay away from them. This not only applies to boats with props, but jet boats as well.
Jets are an alternative solution but only at low speeds. At planing speeds they still present a hazard to anyone hit.
Other devices such as kill switches that shut off the engine when someone falls overboard, or interlocks when the boarding ladder is lowered may be more effective. There are also various alarms that can be had to warn about people in the water, or if the boat is backing.
Prop guards do affect top end and fuel consumption on planing hull boats. They also affect maneuverability, but how much depends on the type of prop guard.
Not all prop guards are created equal. Different types have different characteristics. The type you use depends on what you are trying to do. Some are designed only to keep weeds and debris out of the prop. Others are designed to prevent people from getting body parts in the prop. So the prop guard has be chosen for it's function.
There are significant differences between prop guards and nozzles designed to improve the efficiency of the propeller. The two should not be confused. They do two completely different functions.
Believe it or not research has been (and probably still is) done on ways to detect people in the water by a speeding boat, and immediately stop the prop. Unfortunately this doesn't work very well. Nothing useful has come out of it yet. Forwarding Looking Sonar simple doesn't give enough warning time, not even for rocks and logs and such that present much better targets than humans., except at very low speeds.
Last but not least by any means, the market. On the whole, boat owners simply don't want them. Prop guards have been available as an option from most outboard manufacturers for over 30 years. Some boat manufacturers offer them too. There are a variety of prop guards available on the aftermarket. Hardly anyone buys them. Why this is, who knows. Perhaps most boat owners don't know they are available. The engine makers aren't pushing them either. But my sincere opinion is most people don't want them until something catastrophic happens.
Prop strikes are not rare. They are a small number of the total accidents. In 2010 out of 4604 reported accidents there were 49 struck by propeller accidents and 31 struck by vessel accidents. 1 of those was a fatality. But unfortunately when they do they are almost always catastrophic for the injured person resulting in permanent disabilities and life long need for medical care.
