Time Machine Ep1 Wave Rover reports from the Future about Buoyancy Foam 

I wouldn't take that thing in a swimming pool w/o closed cell foam, but hey it's your life. Mrs. Rover must know the insurance status.

Alan. I don't blame you for not wanting to fill with marine foam. I've had issues with it in the past, especially on plywood/epoxy boats. I like the idea of an inspection port and ping-pong balls or plastic bottles. However, one problem is you would lose your floatation bottles if you are holed. Another problem with this is there will be air space voids around the bottles. Air contains moisture. So as those spaces cool and warm there will be condensation inside the compartments. And on hot days pressure will build up inside the space. I have a 16 ft rowboat I built with floatation compartments. On warm days I can hear the air rush out of the space when I unscrew the lids and vice versa on cold days. So there is a good argument to fill the entire void with foam. Another option would be to make a large plywood lid that is removable using weatherstripping and screws. This would allow you to put in removable foam blocks. I would NOT use the white styrofoam as it sucks up too much moisture. Using XPS (extruded polystyrene) foam works awesome. You can trim, sand and shape the stuff pretty easily. You can even glue it together with epoxy or just roll a barrier coat of epoxy on it to doubly make sure it does not suck up moisture. I used the pink stuff from home depot many times. It comes in 4 ft x 8 ft sheets and 1 to 2 inches thick. I epoxied layers together to make larger blocks that fit voids perfectly. I have four of them on our dock that I coated with epoxy (as a barrier coat) and painted with rustoleum enamel paint. They have been left in the rainy weather of the Pacific Northwest for over 5 years and show zero signs of moisture absorbtion. I stack boats on them and kick and slide them around all the time. They are incredibly durable. A really nice option I think. I prefer the XPS over the pour in marine foam. It is so incredibly strong (you can jump on the stuff with zero crush). I actually would not have a problem permanently filling the void with XPS (coated and set in place with thickened epoxy). This way you know the entire void is completely and perfectly filled with zero air space. Then seal it off permanently. Even if you were holed, I am very confident this foam will stay right where you put it, it will maintain structural integrity and prevent water from entering. In fact, your boat will be stronger and more impact resistant. Hope this helps you decide.

I sealed the sole on the boat I built and filled it with foam. I wish I hadn't. I've worried about water getting into it ever since I built it. The general rule is "if water can get in, it will". If I were to build another boat, I'd make every compartment accessible.

Positive foam flotation is the way to go👍 on my McGregor 26X❤️ my compartments are full of sheets of closed cell foam The boat is my life raft.

Alan, my best suggestion would be to fill that area with an INFLATABLE EXERCISE BALL. They can be found in different sizes and are inflatable so they could be removed from a hatch after deflating and allow inspection of this area. Most balls brag of 2000 lb breaking strength!

What ever you use make it removable for easy inspection and repair if ever needed.

I haven't checked all of the other replies Alan, but I use blown up wine bladders, from 4L bag in a box wine, for my Nordica 16 & my kayaks. Most of them seem to hold the air really well over multiple seasons & they can be retrieved easily as the spigots give something to grab on to. If you use an inspection hatch, then put the deflated bladder into the hole with the spigot facing up; you can then inflate it with about 3 or 4 big breaths, release the button & drop it in. I think that your fully enclosed bulkheads fore & aft would be perfect locations for their use as they can't escape.

I like idea of many small watertight compartments in addition to watertight bulkheads. Something like James Baldwin did on his Pearson Triton Atom. It not only add to the buoyancy but also if there is a leak it can be contained.

You could consider 2"foam board insulation. It's cheap, easily cut into shapes that can be stacked in your void areas, and won't absorb water. If you want to be extra careful about water absorption it can be given a coat of epoxy. This is what's recommended by Chesapeake Light Craft for their dinghy floatation, and having done this myself, I can recommend it as a good option. You probably know this, but I would steer clear of expanding polyurethane foam for many reasons (which I can explain in another comment if you wish). Project is looking great!

+1 for: Plastic bottles, empty, lids on. Max disp for min weight, near indestructible, and free. Thermal expansion? Insulate the space they are in. Put them into plastic bags, making large multi bottle bundles which could not get out of a hole in the hull. Bundle could even be tied off to inner bulkhead.

The beauty of a time machine is you call it any day you want and be there. Have a good week Alan.

I’m using 2 litre plastic milk bottles packed in tight no foam.

Foam doesn't increase buoyancy. It excludes water should you be holed. Foam has weight, so it decreases your weight-carrying capacity a bit. The boat will actually float a little lower on its lines with foam. Since what you're trying to do is exclude water if you're holed, it doesn't make much sense to go far above the waterline with foam. Your hull is actually pretty heavily built, so foam won't give it much extra stiffness or impact resistance. The naval architect has already done that calculation to determine the hull thickness and panel dimensions. Foam would insulate you from cold water, and hopefully reduce condensation, but maybe not. I've thought about it for my catamaran hulls, especially forward where I might impact a log floating on the Salish Sea. Right now I'm leaning toward either removable foam blocks or those little plastice water bottles with the caps on contained under a glassed ply deck with a deck plate to remove them for inspection. It's not necessary to exclude all the water - just enough that flooding the compartment won't sink you. As I'm sure you learned in the navy, you don't have to stop the water coming in completely - just slow it down enough for the pumps to keep up (I've done those drills in the simulator at Naval Station San Diego during my time in the U.S. Navy). Since your bow is pointy, the impact is likely to take place on one side, so a fore-aft bulkhead from the stem to the first bulkhead extending up to a little above the waterline would further limit water ingress without adding a lot of weight, and would support your ground tackle better. The extra concern you have is that unlike my catamaran, you have a big, non-floaty object hanging on the bottom (the keel) trying to drag you under at all times. Again, you need enough floatation that if you whack a log or shipping container, you don't have so much water pouring in that the waterline rises above the companionway or an open hatch or portlight.

I read through most of the comments. Personally I wouldn't use foam but if using it put it in plastic bags. All foam will absorb moisture evidentially. I have seen boats rotting from foam against plywood and corrosion on metal. Someone suggested a exercise ball. Good idea. low weight and won't be lost is boat is punctured. Plastic bottles will work and a few on the bottom can be filled with water. We call that a twofer.

For the buoyancy, Roger Taylor on MingMing filled plastic bottles with expanding foam and stacked them in the lockers (I guess the expanding foam increased the buoyancy cf. just empty bottles? Another alternative is canoe/kayak bouyancy bags that are handily shaped into triangular wedges and you can deflate them to inspect the space (or even to use the space for storage if you were coastal cruising for a bit).

Plastic bottles sound the way to go to me, filling them with foam only ads to their weight and reduces their buoyancy so I wouldn't do that unless you were worried that they wouldn't seal tightly. One idea, though it is admittedly overkill, is first put in a mesh closeable bag (like a huge mesh laundry bag) in the void space and then fill it with the bottles. This way even with a huge hole there is no chance of individual bottles making their way out of the space through the hole. This might also make them easier to fish out when you want to do an inspection. Granted the likely hood of a hole that large is pretty tiny. Another fun filler material are the round plastic balls they use in children's play areas, that way you can practice your juggling with them when at anchor.

For my build the method I decided on is to fill the space with plastic bottles, and have an inspection hatch for the compartment so that you can inspect and clean the space. A large net bag can contain the bottles so that if you get holed they won't float away 1 by 1. PS please send stock tips from the future.

On a small boat I built I packed void spaces with shipping foam peanuts easy to remove if needed too !

I had suggested to another builder to use a netting to confine the empty bottles in that hatch. This is to prevent the bottles from floating out in case the breach in the outter hull is big enogh to let them. Naturally the netting will be best anchored to the inside bulk head so that the net and its content doesnt float away through a big eneough gash

God I am truly loving this boat build. Like the time jump as well.

I would definitely go along the pop bottle route. I've seen what happens to foam in a supposedly watertight void on a plywood boat. Basically it turned into a big, damp sponge. The space around the pop bottles will allow for air to circulate and, as you say, the bottles can be lifted out to inspect and maintain the area.

They say a potato will float in salt water, so you can fill the stern cavity with PEI spuds...bonus is you can eat them along the way (within reason)...lol. Alan, I know you are a very busy man, but I think you & Mrs Rover should have the Wave Rover 650 logo put onto t-shirts & caps. I love the design & colours of it. Enjoyed your time machine update...thanks for sharing!

Regarding bouyancy aid in the bow I like the pop bottle idea, or perhaps polystyrene cubes, but I would place them in a stong net. In case a hole is created separate bottles would just pop out, when in a net a smaller hole means the bottles are kept inside. Having an inspection possibility is great.

"The Wave Rover Navy"!!!! I love it!

This is extremely crucial .and there are 2ways to do it . 1 .fill it with closed cell foam like in the Plan. Because in case of a puncture or a crash the cavity won't be able to fill with water and weigh the boat down.and you will still keep the buoyancy of the boat 2.dont fill, reinforce it and make it a water tight compartment. this is risky because if anything to that compartment you just lost the positive buoyancy of the boat. I've seen some racing boats the did this void and it works fine but remember that twist hach is made to inspect ,the racing boats use a more robust twist hatch ,i don't remember the brand but they are sold to life boats manufacturers

If you refer to sailing ruby 2 there was a Seawind collision. The bulk head was very near the bow . This bulkhead prevent the yacht from taking on water. I would suggest that additional bulkhead s be inverted and filling these with empty bottles.

Another option that might conform better to the space is a beanbag, preferably one designed for swimming pools. typically they are filled with polystyrene balls which on their own would make a mess, but in the bag should be manageable, also the pool versions are usually made from a cloth that doesn't absorb water. this should be able to fill the space nicely with polystyrene balls but still be easy to remove for inspection, just make sure no sharp edges that would cut the bag.

Thanks for the videos, this series is is invaluable. I am building hull #2 and I plan on using foam filled compartments. it is more expensive but there are three benefits that I want that loose filled floatation devises do not provide. The buckling of the side panels as a failure criteria is virtually eliminated you get a much stiffer bow. Foam will add a damper that will help with sound dampening. 99% water displacement keeps water out of the compartment. All that said you should build the boat you want since your the one that is going to be contemplating it in open water gales. Thanks again for the channel, Tony

Foam will be a good option if you plan to keep the boat for 4 or 5 years, but a nightmare after that time. I bought a 2nd hand ply epoxy boat with solid foam in bow and stern. Never again. You could incorporate many watertight compartments under bunks, behind bulkheads fore and aft. You could fit them all with watertight lids and inspection hatches. Think of all the storage space. When laid up, the inspection hatches could be left off for ventilation. Any void should be well ventilated, at least some of the time. I am sure all this feedback is going to give you a headache. Good luck. I am enjoying the build.

Ping pong balls in the void spaces--you can cover the ones away from the edges with glue to stick them together, if you like.

Thank you for this peek into time😁I hope all is well with you and Mrs Rover💯 I suppose foam would be best if you can't store anything in those spots. Wave Rover is coming along beautifully 💯 Prayers for Ukraine 🙏🙏🙏

Delete the flotation in those areas Make those areas hell for stout by adding an extra layer of a tough but more flexible material such as Kevlar or other more appropriate material delete the foam and use an excellent quality inspection port that is well sealed. You will still need small drain hole to the bilge to allow it to remain dry. Use a 1” layer of insulation foam under the top of that space. Space temperature is absolute zero so the top surfaces loose more heat at night and condense water, best to prevent as much water making in enclosed areas as possible. By using the FG buoyancy construction you keep buoyancy higher in the space where you want it for upright flotation. And you don’t add as much mass high. The bottles inflate and deflate with conditions and probably less than 1/2 of the space will be filled

This was a very entertaining video, Alan. I recall your first boat (mild steel) and taking a large bread knife to cut back all the foam after it had been sprayed in. Regardless of what you decided to do, it will work well for both you and Wave Rover.

Spaces like that well built I would seal with epoxy then paint and put in a good quality waterproof hatch and use it for storage now granted that usually would be low density items generally though for balance you may look at heavier stuff if you were to choose to store pool noodles or water bottles full or empty there so be it. can also be useful for garbage which can be an issue sailing. My reasoning that it can be just a void is that people and you have said it seem to think its easy to puncture ply glass at sea, it just isn't. And the forces required will mean you have much much bigger problems so on the old US Navy risk analysis chart its low risk moderate consequence virtually zero exposure. Versus a potentially useful space for trimming the boat and overflow storage. For what you plan to do your water tight bulkheads is more than ample emergency planning. The strength thing well I accidentally dropped my last boat which was stitch and tape 10 ft onto a concrete pad there were cracks around the forward bulkhead and I immediately though OH well that's new bulkhead minimum and maybe new panels etc so started grinding out the tabbing in preparation inside and outside I found no delam no problems with glass or ply only cracks were in the paintwork really it was paint delaminating from the epoxy glass. Gave me huge confidence in that hard working boat. I have repaired other boats with foam in the dead areas and found it full of water harboring all sorts of decomposition etc against the wood, ply does not like water, I only use foam in solid fiberglass boats.

2 litre coke bottles in a net were what I used on my tiki 26

Can't wait to hear more about the junk rig sail. This is a cool looking mini 650.

Fill them will ball pit balls, but put them in net bags cause if you do get a hole bigger than a ball they'll just spill out, but if they in little net bags like onions and potatoes come in they will stay together.

The total volume of the watertight spaces should be divided into 42 parts and used to store bowls of petunias.

Hello colleague (I am also starting the construction of a sailboat in laminated wood) I have the same doubt: bottles or foam. It just occurred to me: a single piece of removable foam. Externally laminated with fiberglass or epoxy. A large lid with many screws (can be from the bow deck or from the inside) You could take out that huge piece of foam, inspect, do some maintenance, and relock. Excuse my bad use of English. Greetings from Buenos Aires

Fill the space with empty drink bottles (lids on!). That's what I'll be doing - I've already started collecting used 1-1/4 - litre soda water bottles for the purpose. If you need extra water capacity, you can dig a few bottles out.

Good to see RW progress. Appropriate song..

How about using plastic balls. About tennis ball size, bright yellow, in case the worst happens. They would be easy to remove for maintenance and should be quite cheap or alternatively table tennis balls. Thanks Alan the channel is always informative and entertaining. Best wishes Brian Hay

add a net to the bow 2L bottles, in case of impact your flotation won't float away

You could use a hatch made of ply, screwed into place. Through this hatch, you could instal and remove blocks of scrap polystyrene (each block, about the size of a loaf of bread, depending on the size of the hatch, and numbered, and hotwired to shape to completely fill the void). Polystyrene or other light, non absorbent foam can generally be picked up here and there for very little. 2 or 3 litre milk bottles also do the job for spaces with fairly square profiles. 2 litre bottles tend to fit neatly through a screw in port. If you're going to make the space truly airtight, you want to exclude the air (with foam), as much as possible, as differential pressures can place enormous stresses on flatish panels. Changes in temperature and atmospheric pressure..... if the area is full of bouyant material, it can be allowed to breathe.

I like the idea of a big water tight inspection hatch. I think you could use those places for storage. If you have a hole on the hull, because yoe hited something, is not a problem is that particular section gets fluded. Yo DO wan to make sure the water doesn't mooves farther into the boat. Like bamboo.

Get a bunch of bottled water bottles, un cap them, put them in a refrigerator, the recap them. They weigh just a few grams apiece. Fill your void with them. They will be easy to remove through the inspection hatch, and you can probably get them for free.

Packing peanuts will fill the volume with little weight. Great Channel.

Leave them empty but fully sealed. This will be the strongest, most watertight, lightest weight (in the ends where it counts most), and cheapest option. Don't bother with any foam or bottles. The added weight and cost of expanding foam won't give you any more buoyancy. Don't add an inspection hatch. None of them are truly watertight. If you need to inspect at some point in the boat's lifetime (unlikely), then cut them open.

I saw a new boat with foam sections cut to fit and numbered.

Isn't foam able to encapsulate water in quite large quantities without you knowing it and also feel dry on the surface. I've seen a number of videos here on YT where using XPS foam for house insulation is a bad choice. How about using balls from a childrens ball pit and an inspection hatch? In that case you can have a large bag of extra balls in some other storage area if some starts to leak and as an extra buoyancy.

I have a sinking feeling (excuse the irony) every time I think about the foam filled partitions in my boat. When I get back on board in the next few weeks I'll take a screwdriver or saw just to take a look. Hopefully I will find sheet material and not dreadful expanding foam. The previous owner fitted my 20' boat with a crash bulkhead and floatation compartments but although well intentioned it makes alterations difficult, never mind keeping an eye on fittings to check for leaks. I'd rather know, you know? Whatever material you choose something which can be removed for simple maintainance seems a more seamanlike approach. Also the idea of indefinite floatation using closed cell foam seems unneccesary - what good is a permanently floating wreck if it comes to that?

Living on PEI ... Go to a dairy. Price the bags they put milk in... They hold a litre and a third and they are tough as nails and fill any void ... Just saying

I don’t know if this would work but how about sheets of bulk styrofoam cut into pieces to fit the spaces. It seems to me that it would be an easy and inexpensive way to do it. Just take each piece cut and formed to fit then stack them up.

Styrofoam packaging Material,the ones that are 1×0.5 Inch ? They fill the space really good and are easy removable and super cheap??

Consider that removable flotation small enough to fit through small inspection port can also fit through same sized hole in hull??

Pop bottles in nylon net bags. Recycle.

As you’re only filling the bottom half (or less?) of those areas surely two part expanding foam is not that expensive? What cost are we actually talking about here? On things that just get sealed away and “not used” it’s tempting to find cheaper alternatives - I get it. I’d be thinking keep it simple and real cheap. If not a complete void use small bottles in a net. That way if you’re in a collision at least 75% of the space will still be air and not water. If you end up spending money on a cheaper alternative to foam, it may not work as well as expected anyway, or have other issues.

How about foam in a plastic bag/liner. With a drain hole in the bottom to the bildge.

i vote for xps boards, shaped to the whole - then the rest can be filled with xps glue, to eliminate air inside the compartment.

Do you really want a buoyant bow? A light bow means a lot of bobbing about on a small boat. That space is usually reserved for storing heavy chain down low. Why not keep it as a chain locker? The chain could be stowed for a long passage and a water tight hatch fitted. You would still have your watertight compartment.

Sorry to inform you but we’re all now in a post Putin hellscape. If you can point you’re time machine two months into the future and report back would be greatly appreciated! How about filling the cavities with urethane sealed recycled wine cork?

empty pop bottles are free could even buy new from a bottler cheap

Love eating a glimpse into the current state of Wave Rover!

Seems like a waste not to use it to store something. Maybe insert a wide, removable, container tube made of PVC pipe, capped water tight at the bottom to maintain buoyancy. You could store extra line or something in there.

pour some closed cell foam. its a "fire and forget" solution.

Before I would make a executive decision on this matter I would like to see a diagram of the interior layout. Just saying.

I was in the Navy as well. First, the 16 water-tight compartments did not save the Titanic, so with that in mind, it might not help you at all. That said, I would make sure they are truely water-tight, but filled with air and a water-tight access hatch. Pre- plumb them with water evac hoses with one way valves and shut-off. In this way you can control how much water you allow to main bilge pump area pickup, pump out and repeat while being in full control (well that is relative I guess). In the mean time, while you are not flooded or damaged, you can store some gear in water-tight containers in these areas, but not more than 1/3 of volume.

No to expanding foam. Plastic bottles sound interesting. 🐟

What about coconuts? Theyre truely watertight and could be used for survival purposes, just in case…🤪

Kayakers use air bladders

Use construction spray foam in those void areas. It is quite dense and cheap, and waterproof.

balls have an 35 percent void ratio.

Do foam o time to cheep out

Polystyrene.

Don’t cheap out

Great way to recycle packaging peanuts. Get em 4 free.

Ping pong balls

I've use polystyrene pieces and then put pouring foam over it they go together with out a problem saves a lot of expensive two pack foam I all so put some sort of breather if I close an area of with out foam

Fill the voids with pingpong balls. Seriously.

Ping Pong balls

Hey Alan. Are Deleting my Comments? My idea of the rubber Bladder Tank May be a light High but it the safest to the Environment and will not me harm by Saltwater. You buy Chemical Bladder Tanks . And you can put these in All your areas. They have different SizE I still don’t understand what someone is deleting my Comments. Gory

The only correct method is to use 2 component foam . Everything else is rubbish

I dont get it ! In the last video you showed us, how to do the epoxy fillets, whixh is not very difficult, and here, boummm, the bulkheads are already in place ! My proposition : Rip the bloody bulkheads out again and show us properly, how you put them in place . There is no time machine, man, he, he ! 😄