D shape foam vs inflatable

[Pauritus]

Hi all.

We were planning on purchasing a RHIB, and a bidder suggested a "D" style foam filled tube with an air bladder in the centre. Is this a good idea relative to inflatables?

The obvious question is I am sure someone here will ask is.... what do we want the boat for?

We are looking for a 19 foot (or so) aluminum hull RHIB to use on the Great Lakes (in US and Canada waters), and landing immediately offshore of islands (some rocky) to do sampling on the islands. We wanted a RHIB for better safety in case of bad conditions.

This isn't a pleasure craft.

I know little of these styles. What I have gathered is that foam tubes add more weight, and perhaps ride a bit rougher than inflatables, but are more robust (as they still provide more buoyancy if punctured than inflatables), and they give a bit more internal beam.

I understand that D shapes are more aesthetic pleasing, but that is of little consideration.

Thoughts anyone?

[909]

I have never in my life seen a punctured inflatable ever.

[Pauritus]

Neither have I.

I know one person who was in one, however, on the coast. I am unsure how they got into those straits, and so do wonder if the RHIB they were using was not well maintained.

Are there downsides to foam D shapes?

[Maximus]

Same as above regarding punctures....
.Good properly made Hyperlon Tubes are very robust!...especially if you go commercial grade and re-enforce with overlays and wear patches to suit your particular needs...although obviously it has and can happen.
As regards Foam collars/tubes I HAVE seen a few ..and two in particular I recall both were high military spec...(they are all considerably more heavy compared to inflatables) and BOTH the military models (relatively new) suffered from water ingress...one to the point that it would hardly plane!! and was basically a right off Tube/Collar wise...BOTH looked perfect to the eye.
The traditional Deep V RIB has much better Sea(lake) Keeping .(especially the sort of size you're looking at)..I know The Great Lakes can have very testing conditions!
Being lighter probably cheaper (for top spec in Both designs)...easier /better handling in the rough ..more buoyancy...softer ride..much easier to repair (if needed) and better performance/economy for the same H.P. and probably a much wider/better re-sale market if you want to up grade in the future.
With an Alloy Hull for Beaching/Landing and as you've said and The Tubes tailored to your needs/purpose I for one wouldn't worry about The Hyperlon tubes being a weak link or point of concern.
Good luck and let us know how it pans out.

[Poly]

What would the impact on your service be if you were to arrive at the boat, discover a puncture and be unable to go out for say 24/48 hours whilst you wait for a robust fix?*

If the answer is you’ll be in deep bother, breaching some legal/contract obligation to collect samples then I’d perhaps consider foam filled tubes. Otherwise if it’s just an inconvenience I’d not bother - the only people I am aware of using foam are military/law enforcement (where air filled me be vulnerable to attack) or fast rescue craft on some vessels (where an FRC out of action can limit the operating range of a much larger vessel costing thousands). If you are unlucky enough to be in that camp then presumably you need to think spare engines, batteries etc too - and may be cheaper just getting two identical boats. From what I see where owners are worried about low skilled helms coming alongside rough piers/fish farms etc they tend to miss the foam and go to HDPE sponsons suggesting to me foam filled aren’t actually much more robust just less likely to stop you briefly.


*there are quick fix patches and clamshells around but assume that a seam has blown, a valve needs replaced or with a semi-commercial operation the operating procedures Say you don’t leave port with a quick fix.

[Poly]

Originally Posted by Pauritus

Are there downsides to foam D shapes?

Oh and being cynical - if the vendor is trying to get you to add something to your essential criteria list that most other vendors don’t have - they may not be doing that because you have a genuine need but rather because once it’s on your spec it locks the competition our and lets them have more control of price…. Of course it may be that your public procurement is different to ours, but I suspect this practice is rife in public procurement everywhere!

[GuyC]

The RNLI E-Class, the ones on the Thames have foam filled tubes I suspect to stop them being punctured by debris in the river.

You could get a HDPE boat like a Tidemans or similar.