Any RIB owner/operators willing help an undergraduate engineering team?

Hello Sirs and Madams,

I'm an undergraduate Mechanical Engineering student at UBC in Vancouver, BC, Canada. In the final year of our degree, all engineering students are required to complete a culminating design project for a real-world client. My team has been engaged by a local rigid hull inflatable boat manufacturer to create a vessel-integrated, automated collar inflation and pressure monitoring system.

As part of our project requirements, my team is required to carry out a user needs assessment, as well as create a market assessment. We've experienced considerable difficulty identifying local owner/operators willing to have a conversation with us, so we have decided to look slightly further abroad.

I was hoping that some of you fine, upstanding forum members, preferably those among you who own/operate/maintain RIBs, would be willing to answer some basic questions regarding your current methods for collar pressure maintenance, as well as your opinions regarding what features/functionality you would like to see in an on-board, automated system.

My team and I would very appreciative if you could answer all, or a portion thereof, of the following questions:

1) What size of RIB do you own/operate?

2) How many compartments constitute that vessel's collar?

3) What is the general category of use for the vessel? Recreational? Commercial/Industrial? Enforcement/SAR?

4) What equipment and methods do you currently employ to inflate/maintain the compartment pressures? For example: How do you assess collar pressures? By 'feel'? A portable or permanently installed gauge? When required, how do you top up the compartments? A foot pump? Portable compressor (DC or AC supplied)? Compressed gas cylinders? On-board compressor and distribution system?

5) Approximately how much did your current system cost to purchase?

6) How frequently do you check and/or top up the pressure in the collar?

7) With your current system, approximately how long does this process take on average? Please include time to assess pressures, set up your inflation system, inflate the collar compartments, and take down.

8) On a scale of 1-10, how satisfied are you with your current system? We'd appreciate any justification you are willing to provide. What do you specifically like or dislike about it?

9) How interested would you be in replacing your current system with one that would not require bringing any equipment to the vessel, would automatically alert the operator to low collar pressures, and could quickly inflate the collar to specified pressure with a single press of a button? This could be done dockside or on the water.

10) Could you suggest any specific functionality or features that would, in your opinion, add significant value to such as system?

11) Could you estimate the total cost (system + installation) at which such a system would become significantly less appealing than your original assessment? (I realize cheaper is always better, but at what point would cost prevent you from seriously considering purchasing such a system?)

Thank you very much for taking the time to read this extensive post, and my team and I would be indebted to any of you able and willing to respond.

If anyone believes that this post would be appropriate for posting in another sub-forum/topic where it may be viewed/responded to more frequently, please let me know.

 

Very interesting topic.
I contemplated making a prototype of a solar powered pressure regulator with parts similar to those in an electronic blood pressure gauge. The device should be permanently attached to the air valve of the bow compartment. Unfortunately I was unable to find a miniature air pump with adequate life expectancy.

My 6m. RIB has a 5 compartments tube that I inflate with a foot pump, no gauge.
The challenge is to find an acceptable minimum pressure in shadow without exceeding a maximum in bright sunlight.
An automatic system needs no operator alert but should release air when necessary.

A good place for your post may be http://www.rib.net/

 

The answer may be an air pressure relief valve calibrated to the maximum desired pressure.

See http://www.generant.com/relief-valve.shtml

http://www.generant.com/vrv.shtml

 

With the boat in the water, it may take days/weeks before there is a need to top up the tubes.

If you beach the boat, trailer etc. You must deflate the tubes a bit because under the sun the air pressure will quickly rise above the recommended.
Then, at night the tubes will look underinflated.

 

I need such a valve that puts the air back in in the morning!

 

You would need a pump set to minimum pressure that comes on automatically to compliment the valve set to open above the maximum setting of the pump. They would function as a team.

 

I think you need five pumps because one pump will connect all compartments and compromise the boat's safety.

Its getting complicated and more of a pita than a convenience.
Considering the marine environment it will also be expensive.

 

Thanks for the responses everyone. Feel free to keep them coming. I'm bound by an NDA so I can't really discuss the specifics about functionality and how it will all be achieved, but rest assured we're already thinking about your safety/practicality concerns.

 

One pump into a manifold with check valves on the lines to each compartment so the compartments will act independently of one another in case of a rupture will take care of the chambers being inflated by one pump
Each compartment will require a high pressure relief valve due to the increase in pressure due to ambient temperatures but these will be cheap.

One pressure switch to keep the manifold at its design pressure and hence all the compartments the same.

If you discard the concept of a foot/hand pump and decide that you will afford an electric pump as the prime inflation device, then the cost will not be significant. Ie if 5 compartments, 5 high pressure relief valves, one design pressure valve in the manifold, some check valves and lines.
Of course you will have to add in a battery and charging system

So 5 high pressure relief valves, one design pressure valve, battery, charge system (solar) and some lines. (assuming that you WERE prepared to pay for the original electric pump as a normal system.
Estimated cost $400 CAD
If the rib is big enough that it will have an electric start outboard on it, then the charging system and battery cost drops off the total and you might be able to do it for about $150

 

The separation between the compartments is quite flexible. I use only the bow compartment to increase/reduce pressure during the summer season.

 

5 lines, from the pump, each having one way valves would cut the risk. Unlikely, but not impossible, that more than one chamber would catastrophically fail.

 

Latest RIB purchased has over pressure valves which bleed air out if it rises above about 3.5 PSI (I think) or whatever the manufacturer has set. It does work in the southern UK, and when it bleeds the air it does so in a mannner wich will require a small ammount of topping up if it is a bit cooler. Daytime diurnal range can be approx 20+ deg C and we have had over 30 deg C in September in the shade when this effect has been observed.

Vessel concerned Humber 4.3m Assault RIB Suzuki 25Hp.

http://www.humberinflatables.co.uk/assault.html

This boat replaced a similar previous one which was getting a bit tired after 13 years good service. It was still in good condition, engine hours around 250-300 pa. FWIW it had a Mariner 25 Hp complete with the usual flywheel replacement (magnets disintegrated, though coils were saved!) new voltage regulator, couple of fuel pumps, new starter.

I can probably identify the bleed valves if you would like that information.

 

I have serious doubts about the data you present here.
3.5 Bar is the tire pressure for a light truck, an inflatable is already in the danger zone at 10% of it.
The effect of sun radiation should not be underestimated. On a bright summer day without wind, the tube temperature easily reaches 65 C. Coming from 10 C. at night, the pressure increases with more than 20%. The two rear compartments stay somewhat cooler because they touch the water, the one on the bow definitely needs a relief valve to survive.

 

Ooops thanks for that CDK it should be PSI - I have corrected the post.... which is a just a little lower!. I must be getting to used to metric data....