Floatation foam

[Robert H. Wilkinson]

Hi Colbysmith, in answer to your first question - foam does serve several purposes.
1/ It provides buoyancy in the event of a swamping.
2/ It helps prevent, limit, or isolate water intrusion in the event of a hull breach (holing)
3/ It strengthens the hull, adding rigidity to lessen flexing in a heavy sea.
4/ It gives you a quieter ride (esp. in an aluminum hull)

In answer to your second question - I believe all boats up to 20' are mandated to be built so as to float level if swamped. This may be why the newer 22'CDs don't have it as they are above the 20' limit. I did read here somewhere that CDs have been known to float bow up with the stern under water when swamped. An Armstrong bracket would fix that. This is one thing I like about the 22'Seaskiff (Rosborough) - you can custom order the hull configured for an I/O (full transom) then add an Armstrong bracket with your outboard. Lots more room in the cockpit without the outboard well, and a swim platform (not to mention the other benefits to a bracket)

Last summer I met a fellow boater from Buffalo who told me an interesting story. He had just exited the Welland canal into Lake Ontario when he was swamped by what he described as 2 converging waves. Despite loosing his windshield, his glasses and his Sea Ray being swamped - his engine kept running - his pumps kept pumping and with him bailing (his wife took the helm because he was blind without his glasses) they were able to clear the hull of water and continue under their own power back into port!! Without Sea Ray's use of floatation foam I may not have ever heard that story!

Regards, Rob

 

[thataway]

The Coast Guard Boat Builders handbook addresses Floration thus in Section F:

Subpart F - Flotation Requirements for Inboards, Inboard/Outdrive, and Airboats
FEDERAL LAW

183.101 - Applicability

This subpart applies to monohull inboard boats, inboard/outdrive boats, and airboats less than 20 feet in length, except sailboats, canoes, kayaks, inflatable boats, submersibles, surface effect vessels, amphibious vessels, and raceboats.


Discussion:
Monohull inboard, inboard/outboard boats and airboats less than 20 feet in length must comply with a flotation system called Basic Flotation. Basic Flotation contains the requirements and tests. Basic flotation is the simplest type of flotation mode covered in this regulation. It simply requires that the boat be manufactured with sufficient flotation material to keep it afloat in the event of a swamping. It does not, however, require that the boat remain in an upright or indeed any specific position. It may float, and usually does, in a "spar" position, the bow sticking up and the stern sunk. The requirements include some materials tests. Basic Flotation covers this type of flotation.


Subpart G - Flotation Requirements for Outboard Boats Rated for Engines of More Than 2 Horsepower
FEDERAL LAW

183.201 - Applicability

(a) This subpart applies to monohull outboard boats that are:

(1) Less than 20 feet in length; and
(2) Rated for outboard engines of more than 2 horsepower.

(b) This subpart does not apply to sailboats, canoes, kayaks, inflatable boats, submersibles, surface effect vessels, amphibious vessels, and raceboats.


Discussion:
Monohull boats under 20 feet in length and rated for more than two horsepower must comply with the more sophisticated flotation system called Level Flotation. The Level Flotation system requires that the swamped boat, loaded with certain weights representing weight capacity, part of persons capacity and some equipment, must float in an approximately level position and not heel past a certain angle, even when part of the passengers’ weight is on one side of the passenger carrying area. The Level Flotation section covers the requirements and tests to perform.

In reality many vessels do not float upright and level if swamped.

There is a down side of foam in boat hulls, and that is that many "closed cell foams" will in fact adsorb a fair amount of water, and thus not only have as much flotation as touted, but also may increase the weight--in a way which is almost impossible to get rid of short of removing the foam.

In the C Dory 22, the forward part of the hull is quite stiff, since coring stops about where the bulkhead begins. Certainly the way that foam is applied to the 22's and most other C Dory's (I cannot commit on the 16 and 19) it does not give level flotation, nor is it required to.

A boat with a self bailing cockpit (which a few of the C Dory products have) surviving a heavy water intrusion. As for the Sea Ray--it would depend a lot on how much water got into the engine compartment. If there was significant water there, I/O's do not do well, and the engine is well into the bilge in most small Sea Ray I/O's. Thus the assumption that the water from these waves did not find their way into the bilge. Not sure what this story has to do with foam floatation.

Even a Boston Whaler which is "unsinkable" often cannot be run after being swamped and filled with water, even though the engine head is still out of the water.

 

[Robert H. Wilkinson]

Hi Bob, I believe the Sea Ray was an outboard and according to the owner the water was up to the gunales. This lead me to believe that without the added buoyancy afforded by floatation foam he would have probably sunk.

I have also heard of the foam becoming "water logged" :amgry as you mentioned. Mostly the stringer grid foam after numerous owners have drilled into the floor for various reasons.

There are down sides to just about every "good idea"

Regards, Rob

 

[Robert H. Wilkinson]

Hey Bob --- I've been thinking , if you had a boat with the stringer grid cavities full of water logged floatation foam it might actually make it a more sea kindly boat - like the lead keel of a Nordhavn!! :lol: :lol:

On the other hand if was doing its job providing buoyancy - and supposing you were swamped by 1 wave - the second wave might turn you "turtle" because of all that Buoyancy in your keel !! :lol: :lol: :lol:

Opps, I hope Da Nag doesn't have a rule about this safety forrum being serious!!

Regards, Rob

 

[chimoii]

Just a quick comment on Boston Whalers, of which I have owned several. The early models had foam that absorbed water but the later (1990's on) models use a non-absorbing foam.

I have swamped a 13 in 2-3 footers in the middle of the Chesapeake. The wave came over the stern and off the bow. Fortunately the motor kept running so we just put her in gear and most of the water went off the stern. To get a full drain we pulled the plug and put her up on plane. Many times if we were tied up for the night and there was really heavy rain we would just pull the plug and leave her after moving the gear up forward.

The 23 had a wave come over the bow and the stern on separate occasions, both the result of stupid operation. The stern was the worse. I had about 2 ft water in the cockpit and the cabin had about 18 ins., fortunately just below the locker level. I opened the stern door, kicked on the macerate pump in the fish box to help the bilge pumps and then waited. The scuppers drained well. The pumps took almost 15 mins to drain under the cockpit deck.

I am much more careful in the C-D !!!

 

[Robert H. Wilkinson]

Hi Chimo, thanks for the input from our west coast. Its good to know that the newer foam is non absorbing. I have a 1985 Thundercraft that I think has some foam absorption issues. I also had a 1982 Campion hard top with rusted fuel tanks that had gasoline soaked foam under them!! :amgry Good to know the foam in my new Stingray shouldn't suffer from water absorption.

A friend of mine in our local Power/Sail Squadron was out in Lake Ontario fishing in his 19' Aluminum. Due to a "live well malfunction" he started to take on water and ended up with his gunwales floating just above the waters surface. Luckily he was in a protected bay (Hamilton), it was a calm day and someone on shore spotted them and summoned the OPP who towed him in. He was grateful that the foam in his boat did its job. :thup

Regards, Rob

 

[thataway]

Unfortuantely many of the "closed cell foams" which are not supposed to take on water, in fact do take on water; even today. This does not mean that they will not float, but weight will be accumulated and be detrimental to performance. It is not just in the grids and stringers (by the way most Nordhavns rely on active stabilizers or paravanes for stability. Some of the early boats (46's) had ballast, and a few of the newer ones for trim, plus the motor sailors have ballast--but many don't) Although some sailboats use water ballast, it is not as effective as heavy metal ballast--and water in foam will not serve that purpose.

There are a very few outboard powered Sea Rays (mostly bow riders in the 18 foot size, but I have seen some 13's around recently). None of these are particularly seaworthy boats and I would not take one into rough water.

I have rescued two Boston Whalers which were swamped (both with a 13 foot inflatable). The boats were not over their capacity as per plate, but close to it, with both people and gear. Both could have turned into tragedies with loss of life from hypothermia. In both cases the boat full of water was not able to be run. Batteries, and electrical circuits were out. Even if the boat was able to run, it would not be able to plane, as it was floating level with the water. (in one case the crew had abandoned the vessel and swum to rocks.) The point is although a boat will not sink, it may not be functional to get one back to safety. Yes, a lightly loaded open whaler with only a moderate amount of water can be run to get the water out---but if full, and loaded with gear--no.

All in all, keep the water on the outside of the boat!

 

[Robert H. Wilkinson]

Hi Bob, thanks for your input. The gentleman did tell me that he realized shortly after exiting the canal that Lake Ontario was not the place for a 18' bowrider that day! When I met him last year he had a new 24' Sea Ray sun deck - with full camper canvas. I'm still not sure why a middle aged couple who enjoy overnighting on their boat and cruising the great lakes would choose a bow rider?? Especially with all that canvas to contend with!! :?

My comment about water logged foam adding to a boats sea keeping ability by weighting the keel was a joke :lol: :lol:

Good to see somebody that is familiar with Nordhavn's. They are an awesome boat. I would love to crew on 1 of their Trans-Atlantic rallies. In the meantime I will consider myself lucky if I ever actually get to see 1!!

As you said "lets just keep the green water outside our boats" - then we will never have to put our foam to the test!!