Old hypalon and big motors

[copboat]

Hello, new member here and I've got a few questions about a recent purchase of a 22' Nautica from 1999

It's 20yr old hypalon, pretty decent shape for the age. It's lived in Michigan it's whole life and not faded too bad at all

My question is about the glue bonds and what I plan to do to it.

Over the next month I'm going to hang twin 125hp Mercs on the back, a total of 700lbs. Transom is rated for 280hp, boat is rated for 3600lb with a 1200lb dry weight.

Is it possible to push a rib too hard and rip a tube loose from the hull? Has anyone encountered this failure mode from running hard in a strong chop?

[John Kennett]

Yes it's possible, and has happened several times.

Running upwind isn't likely to be a problem, but stuffing the bow at speed in a following sea will show up any weaknesses.

[Poly]

If you are looking to preserve the tubes rather than replace then have a search for “stuffing strap” on here you should find some ideas for something that won’t necessarily stop the failure but at least keep the tubes in place so you get home. Basically it is an extra fixing rope or webbing over the bows of the tube and bolted to the hull on both sides. Not normally seen on leisure ribs as not that pretty and rarely necessary.

[office888]

I'd be more concerned about running the tubes underinflated at speed, causing a rear seam failure.

>3.0 psi is mandatory. You need to check the boat after it's been in the water about 15 min, and the cold water has had time to cool the air, reducing the pressure.

Also, if there's an extreme temp change (IE, nightfall), you probably need to top off before the return trip home.

Buy a 12v electric pump.

[copboat]

Thanks for your replies

Here on Lk Superior stuffing is an issue as the wave period is pretty short relative to height and the waves are pretty "steep". I will look into this "stuffing strap" and see what it involves.

Regarding tube pressure, another challenge for us as well. Lake temps stay pretty cool and air temps vary greatly from day to night. Thank You for the pressure recommendation

Regarding air pump, we are looking to pick up one of those two stage units with pressure regulator built in...What I would like to do is hook up the 3 bladders on each side together and then connect to the pump and have the regulator "close loop" control the pressure. The boat would be run this way - with the pump in the loop

Anyone ever done something similar? I know it would increase the chances of a single point failure but sure would provide even tube pressure in all conditions.

Will those two stage pumps push air push the spring loaded check valves? If so then single point failure (at pump or junction blocks would be negated)

[beamishken]

I'm sure I once read a sales brochure for a rib that was fitted with an automatic tube pressure regulating system which would increase or decrease the tube pressure as required.
Don't know if it was a commercially available kit or something someone had built from scratch.
Seemed like a good idea but never see or heard of another.
Maybe an opening for someone to make a system

[office888]

Originally Posted by beamishken

I'm sure I once read a sales brochure for a rib that was fitted with an automatic tube pressure regulating system which would increase or decrease the tube pressure as required.
Don't know if it was a commercially available kit or something someone had built from scratch.
Seemed like a good idea but never see or heard of another.
Maybe an opening for someone to make a system

Zodiac MilPro.

Uses a non-return valve from a central point, in combination with intercommunicating valve assemblies.

$$$$$$$ pricey

Topping up with a Bravo 12 BST is my preferred method. Just don't let it get drenched with water.