Importance of proper inflation

[jrs_diesel]

All this time I had been under inflating my SIB, until my last outing. I had purchased a pressure gauge to check the tube and keel pressure (wood floor, inflatable V keel). I had been inflating to about 2 PSI by feel, it felt correct, and the boat performed OK. Using the pressure gauge, and bringing the main tubes to 3 PSI, and the keel to 4 PSI, the boat feels and handles a bit better, but the big gain was in speed.

I have a 2 stroke Johnson 9.9, and had previously been unable to hit 20 MPH, 18-19 was the best I got with under inflated tubes. With good pressure, I hit 21.3 MPH!

So the big takeaway here is that inflating the tubes by feel only can be misleading and hurt your boats performance. I had no idea I was under inflating, perhaps out of worry of over inflating and popping a tube.

 

[Sea Rider]

Jrs,

Was that pressure pumped right before sib was water launched ? If not, once sib is floating for some minutes rest to give time for overall pressure to staibilize, top again tubes and keel to those working pressures.

Now you know the better sib handling and speed difference achieved boating top inflated as opposed to under inflated as most sibers do. Thumb pressure testing will not match readings achieved with a presssure gauge ever.

Happy Boating

 

[jrs_diesel]

Yes, the pressure was topped up just prior to launching. I checked the pressure later in the day and it had not changed. Had warm water, a hot day, and full sun.

I agree with you on thumb pressure testing, just not that accurate.

 

[Sea Rider]

I agree with you on thumb pressure testing, just not that accurate.

It's not just a non accurate reading, add uneven pressure inflation on tubes too most of the time. In warmer days overall presssure should stay about same, not on cold days, in which will need to top once on water and probably top again throughout the boating day specially if boating late.

Happy Boating

 

[Chopperbill]

When I called the Saturn distributor to get the scoop on pressure he actually says no need for a gauge with the included hand pump, even the web site said that. He said to pump them until it got difficult to add air. Said tubes have a relief valve so don't worry about popping them. I still look at the gauge but don't know really how accurate it is. He said the max on the Saturn air chart is based mainly for hi pressure electric air pumps, that where you get into trouble. Boat is junk without enough air in them.

 

[Sea Rider]

The Saturn distributer guy who attended should be selling pastry. Only possible if having a exclusive pressure relief valve per tube, not all have one per tube, don't know about Saturn.

It's not same the foot or hand pressure pumped by a light youngster as opposed to a older man. A youngster will probably pump to just 2 PSI, a older one way more easily with less effort. Pumping +,- will depend entirely on age, size, overall weight, foot or hand strenght and pump employed. Personally can inflate with a hand pump to 6.0 PSI easily while other skinny ones not even one third of that pressure.

Inflating sib with a gauge to its working pressure will achieve that glued parts as handles, oar locks, side bumper and even transom stays glued much longer compared to always riding a defletad inflatable.

Happy Boating

 

[Chopperbill]

From Saturns site.

What is the working air pressure, and do I need a pressure gauge?
It is not necessary to have an air pressure gauge to inflate Saturn boats. The boat tubes are equipped with Safety valves that will prevent over-inflation. In general, when you feel that boat tubes/floor are hard to the touch, and it becomes difficult to pump any more air in, that means that the boat is ready.
However, if you are using a high-pressure electric air pump, please use below guidelines to avoid boat over-inflation and consequential damage.

Helpful conversion factors:
1 psi = 0.06895 bar
1 bar = 14.50326 psi
1 kpa = 0.145 psi

 

[Sea Rider]

Does Saturn equip each tube with one over inflation valve ? Have been seeing lately that some manufacturers are adding just 1 overinflation valve on bow tube and none on the rest of tubes. Personally don't like them, prefer to use a pressure gauge on hand pump and monitor pumped air while inflating all tubes gradually to near full working pressure in a merry go round pumping motion. Relief valves don't work with fixed air pressures as one would imagine, say 3.5 PSI. Valves opens and closes at 2 different inside pressures parameters, so will have less than expected.

Happy Boating

 

[Chopperbill]

Only have one pressure relief valve. I also do the ring a round the rosy deal with the gauge

 

[alanfox55]

Here's a nice gauge from NRS.


http://www.nrs.com/product/80008.02/nrs-digital-pressure-gauge

 

[Chopperbill]

Nice gauge, should have got one. I ordered another analog gauge to fit in my hand pump and it is spot on with my other different company gauge. So I'm not going to worry about it any more.