Inflation/Deflation - Elevation (Norcal)

ninjah · 12 May 2014, 21:05

Hello. So, I'm hoping to get some feedback from anyone in CA that takes their ribs up into the Sierra Nevada mountains. Or, anyone that might be able to shed some light.

I'll be traveling mainly from the East Bay area up to Tahoe on occasion along with a lot of the lakes in desolate wilderness. I know it's important that I pay attention to the pressure and make sure to let pressure out before going up in elevation and then stop and put some in on the way back. What I'm not sure about is how much to let out (and for you CA folk) where the best place to do it would be. Someone told me its bad to have the boat under pressurized so I want to make sure I do this right. Is there perhaps some sort of elevation/pressure guide I could refer to?

Thanks for any help.

captnjack · 12 May 2014, 21:16

I'll assume this is a RIB on a trailer...
Just leave it under pressurized on the trailer. The fabric is way too thick to flap around. The risk of bursting it is very significant driving up to someplace like Tahoe.

Its bad to use it under pressurized, storage doesn't matter and it could be completely deflated for months or years with no issues (except mice).

Peter_C · 13 May 2014, 02:04

Is your transom supported by the trailer? Do you have an extra motor support? Which motor do you have? I would assume since you said Tahoe it is a heavier 4 stroke (I wish I had a 4 stroke "most" of the time).

Also how do you strap the boat to the trailer? These all come into play with running very low pressures on the hull as you start up thru Auburn. You could pull over somewhere around 4,500ft and check your pressures quickly. A pressure gauge is critical to the boats performance, and it only takes a minute. Although I would probably just squeeze the tubes and guess for a 1/2 pound or so.

Now that your boat is running have you toured the SF Bay?

Bigtalljv · 13 May 2014, 03:12

I did it last year and it's not so bad. I think I let air out the first time at auburn. I let air out two more times I think. If i do it again I'll bring a pressure gauge and figure out altitudes and pressures. I'm ridiculously conservative/scared about anything going wrong. There are a couple on/off ramps that don't get used much that you can pull off and on the highway in a straight shot.

Also it's not as big an impact but it gets hot out there.

Same coming down, that's not so bad as it just gets to the point the fabric is flapping around a lot or reaching down towards tires. There was a convenient rest stop going down.

Your boat has to be inspected at an inspection station and it's not a quick rubber stamp. They are thorough but that's ok with me. It's such an amazing lake I'd even support banning all outside boats but I'm getting off track. The wait times can be long if they are busy.

There are surprisingly few launch ramps up north. We go up for the Trans-Tahoe swim and that starts at sand harbor just below incline village. That's the best ramp up north. South lake probably has a bunch but I haven't spent a lot if time there

Jason

ninjah · 13 May 2014, 05:23

I have a 40hp mercury, trailered, with a motor support (I assume you mean that bracket that holds it up while towing). The transom is fully supported by the trailer.

Jason, thanks for the tips towing up there, that's what I was hoping for in regard to spots on the way you've found works well to stop. I just ordered a pressure gauge. Lots to learn!

ninjah · 13 May 2014, 05:24

Thanks too Peter

Peter_C · 13 May 2014, 06:53

No issues towing it with low tube pressures since the heavy part, the motor, is fully supported.

Tahoe does require the mussel inspection and they will want a DRY bilge, or a thorough cleaning. I believe there was a $50 or more fee associated with bringing a boat to Tahoe. Most likely you will have to remove your floor to show them underneath. An easy way to re-inflate might be in order.

Fallen Leaf lake cleaned our kayaks with a steam cleaner for free, and they hadn't been in the water for months (Totally dry).

ninjah · 13 May 2014, 14:32

Wow, I didn't realize Tahoe was such a long story. But, obviously in good reason. I'm likely going to stick more to the other lakes up north from me near the base of the Sierra's. Heading to Bullards Bar for a boat in memorial weekend camp trip. Hoping water level is OK(ish)...

captnjack · 13 May 2014, 15:25

Funny thing about those mussel inspections, if the last waterbody you had the boat in was marine they look at you funny and have no idea how that could be. It felt like I was the only person to ever take a boat from Seattle to Yellowstone. IIRC I had to stop 3 times, once in eastern WA, once in ID and again in Yellowstone itself.

Lots of inflating and deflating on this trip (sea level to 6500 ft back down to 1500 then up to 8800ft again, then reverse). So much that inflating and deflating that I put in transom U bolts to avoid having a strap over the tubes ever again. The fabric never flapped but the tie-down strap would get loose on descents.

ninjah · 13 May 2014, 15:46

In regard to monitoring the pressure, I've been considering buying a screw on gauge but the only one I can find is online here: Screw Cap Pressure Gage

Problem is it's going to cost me like $60+ which seems expensive. I'm sure its [well] worth it but can anyone recommend anything else?

Also, captnjack, I'd be curious to see photos of what you did with those Ubolts.

captnjack · 13 May 2014, 16:55

Try this gauge instead.
BRAVO SP-125 Pressure Gauge | West Marine

If you don't put it inline with your pump just plug the extra hole where the hose would go. West Marine also carries a cap/checker type but I couldn't find it on their website.

I will try to take a pic of the U bolts at home. They just go through the top of the transom like on any hard boat. Then 2 ratchet straps hold the transom down to the trailer bunks.

Locozodiac · 13 May 2014, 21:16

What's your altitude between boating points. Are going from sea level to a high altitude ? Accorrding to my Andean Experience with inflatables a sib/rib with its tubes inflated to 3.0 psi at a close garage at 9 K feet and driven to sea level, will arrive with 1.0 psi.

On that matter if you boat all day long at sea level with 3.0 psi and don't deflate sib to same pressure as previously arrived while going to same elevation will burst tubes on its way up.

Need a pressure gauge to be on the safe side specially if ascending from a low to a high altitude, remove engine as transom will rock accordingly along tubes when deflation shines in.

Happy Boating

Locozodiac · 13 May 2014, 21:24

Quote:

Originally Posted by ninjah

In regard to monitoring the pressure, I've been considering buying a screw on gauge but the only one I can find is online here: Screw Cap Pressure Gage

Problem is it's going to cost me like $60+ which seems expensive. I'm sure its [well] worth it but can anyone recommend anything else?

Zodiac has its own pressure gauges, no other one that works on Halkey Roberts valve will work/read. Better ask before you buy if that model will match your Zodiac sib valves. A pressure gauge is the way to go if don't want to hear a load kabummm on it's way up.

Happy Boating

Bigtalljv · 13 May 2014, 22:07

Are you carbureted or fuel injected? The power loss on my old carbureted Honda was amazing. It was running very rich due to the altitude. I forget the numbers but the altitude and power loss were right on.

ncp · 13 May 2014, 22:24

Heed everyone's advice.

I started at 39 degrees in the AM in southern OR with super soft, flaccid tubes -headed south on the 5 - hit 70 degree at the summit by Lake Shasta - popped a 4 ft gash in my tube.

Peter_C · 14 May 2014, 03:01

Quote:

Originally Posted by ninjah

Also, captnjack, I'd be curious to see photos of what you did with those Ubolts.

I am not captnjack, but I do have U-bolts in my boat. Of course they are reversed to be used as lifting rings for hoist launch at Still Water Cove and Pt Arena (They have backers on them now). On the outside I have an eye that can be used for attaching most anything like a wakeboard rope. My boat came with two galvanized eye bolts in the transom. The u-bolts now go thru the eye bolts original location. I would recommend putting some u-bolts on the transom if you don't currently have some. I got mine from Amazon.

You can see one of mine on the upper left of my transom. The right one is hidden by the elephant trunk. My tie off points that I use when trailering are clearly my wheel brackets. I have an ugly boat, and I don't care, as it gets the job done!

jyasaki · 14 May 2014, 15:21

For lowering the pressure, I don't think a gauge is necessary (though you may want one for the final filling.) Get a feel for how stiff the tubes are for normal running conditions, and deflate so you get 3 to 4 times the deflection when bashing the tube with your fist (or other measurement - it's not that critical.) Should be softer than when you're on the water, but not so soft that it flaps around in air wake from the car.

Last time I went to Tahoe, I left Oakland in 65ish degrees, hit 90s to 100s through Sacto, then hit the hills. I must have dropped pressure 6 times to the pass, then had to stop and refill on the way back down to the lake (temp back to the 70s.) That was prior to the mussel inspections, so no experience with that.

jky

ninjah · 16 May 2014, 16:29

Hey guys. So I'm headed to a lake at 2000ft (from 20ft) for memorial day. I expect the temperature to start around 70-75 and get close to the 90s+. Any ideas on what pressure to start at and at what temp/elevation to start letting air out?

Bigtalljv · 16 May 2014, 16:36

better safe than sorry. I usually deflate them to squishy but not floppy to start with and with rising temps and altitudes when I see they have regained their form I usually stop and check them. It's all very off the cuff.

Temperatures have been a bigger issue for me. On the trips to the Channel islands I leave the water at 50 and foggy and can drive to 100+ in the valleys.

Again better safe than sorry. Take it easy, you are towing a boat so another 10 minutes in stops won't be the end of the world.
Jason