Bestevaer 49ST

[noelex 77]

Originally Posted by HankOnthewater

A good reason to go to the Hiswa in Holland where this boat will be on display, plus of course a dozen other ones that will cause the customary drooling.

HISWA is a good venue, although nowhere near the size of the enormous indoor shows like Dusseldorf. It is helpful to see yachts in the water with their normal mast and rigging in place and you can do this at HISWA. Last year it was hosted by Amsterdam Marina and we crewed on one of the KM boats that sailed to the show (ours was not finished at this stage). Sailing into a major city such as Amsterdam is a special experience. This year I think another venue is hosting the show, but I presume the show itself will be similar.

KM also have an open day, usually in April, which is the ideal venue if you want to see many aluminium boats similar to ours.

[noelex 77]

Originally Posted by kmacdonald

I'm not trying to second guess your decision to use Gel batteries but did you consider LiFePO4 batteries? If so did the reliability and simplicity of Gel win out? For what little it's worth, I would have chosen AGM or Gel also.

It seems a hot topic with passionate views on both sides .

We have had such great life and overall performance with gel batteries on our previous boats that this proven technology was always going to be hard to beat, although as well as lithium we also considered the carbon foam, and also the 2V spiral wound gel batteries.

Lithium batteries have some significant advantages over lead acid, but the high charge acceptance that is such a game changer on generator equipped boats, does not apply to vessels like ours that derive nearly all their power from solar. The loss of the ability to maintain a high SOC with trickle charging also minimises the effective capacity advantage of lithium batteries for solar boats. There are still some things in favour of lithium, such as high battery efficiency (a big plus in my view) and voltage stability (although we have few high draw appliances and 24v helps minimise this latter issue). Likewise the weight and space savings that are appealing for catamarans do not have the same significance in our vessel.

The major problems are the added complexity and reduced reliability of the BMS and balancing system. KISS is not going to work with these batteries. There are other annoying problems such as difficulty replacing batteries in remote places and the insurance issue. Finally, charging lithium batteries is difficult at very low temperatures, which goes against the philosophy of building a boat that can go anywhere.

Hopefully, we will not have to consider replacement batteries for some time and by this stage many of the above problems will be less of an issue. So lithium batteries may well be the replacement. By this stage it will also be clearer what the true cycle life is in marine applications. Manufacturer’s specifications and accelelarated cycle life tests often bear little resemblance to real life in this area.

[noelex 77]

On our old boat we had an anchor drag alarm on a Furuno unit that could be seen when sleeping. It was surprisingly useful.

Our new boat has a Vesper Vision. This unit has a great anchor drag alarm, and even better will communicate via wifi and relay all its information.

So I used an old mobile phone (again) and mounted it in the hatch that is directly above our heads while sleeping. The Vesper will also relay NMEA information such as windspeed, but you need to push a button to switch displays (or have two phones) to see both.

I mounted the phone on a simple hardwood bracket angled down so that it faces us when sleeping. The bracket plugs into one of the sockets for the removable security bars. I added a safety line to ensure if it was ever knocked it could not land on our heads. The bracket has USB battery pack just behind the phone, which ensures it lasts all night. I asked KM to install some power sockets near each of the hatches, primarily for fans in hot weather. They could also be used to power the phone, but for a low draw appliance such as this, the battery pack works well and the display can be easily moved.

The phone and bracket can also be used in one of the pilothouse hatches for an overhead display of windspeed, heading, depth etc. Cool .

The photos below show both screens. Details of one of the beautiful custom hatches made by KM can also be seen. This has a glass (not plastic) insert that means no scratches or UV deterioration. The four stainless handles and thick aluminium construction ensure the hatch can be dogged down tight, so no leaks.

[a64pilot]

I had not thought to use a phone, I use an iPad and a RAM mount

[DavidSaunders]

Originally Posted by noelex 77

The four stainless handles and thick aluminium construction ensure the hatch can be dogged down tight, so no leaks.

Noelex and SWL, Thank you for sharing your build with us. I hope you are well and enjoying your amazing boat even more now that you have lived with it for a year.

I am specifically curious about what type of gasket KM used for the hatches. I tried to order some epdm for my window gaskets, but what i got was way too dense and didn't compress very much at all, so is unuseable for the purpose. Ideally the material would be resistant to sun/heat/cold/salt and compressible enough, but not too soft....

Are the hatches all custom built? I'd love to see a detail shot of the gasket interface if that's not imposing on your already generous efforts too much.

Thanks,
David

[noelex 77]

Thanks David

Yes, the hatches have all been custom made by KM. We were tired of hatches that leak and plastic lenses that scratch and craze so we requested “submarine hatches”.

The gasket is rubber with a simple flat profile that fits into a groove. I have been meaning to ask what brand etc it is so I can purchase some spare. The hatches have been totally waterproof, but I think this more related to the construction rather than the gasket. The construction steps taken to ensure waterproofness were:

1. Four stainless steel handles. This enables the hatch to tightened down hard.
2. A thick aluminium frame: the hatch frame has much less flex than normal, once again increasing the pressure on the gasket.
3. The handles don’t penetrate the hatches. The handle axels are welded to the frame and do not penetrate the top surface, therefore the handles can never leak.
4. The hatches are raised 50mm off the deck, so most water on the deck does not even reach the hatch seal.
5. The hatch frame is welded to the deck so there is no possibility of leaks at the hatch/deck join.
6. Glass lenses or solid aluminium. The pilothouse windows provide plenty of light so many of the hatches are solid aluminium. This also means these hatches can be fully insulated, eliminating condensation.
7. Where light is needed glass is used, primarily to avoid scratching and UV deterioration, but glass expands less and seems to stick to sealants better than plastic. A wide flange with thick glass is used so there is plenty of sealant area.

Below is a photo of the outside of the front hatch, during construction before the glass is fitted. The construction method outlined above gives a smaller glass area, but the hatch has been made larger (600 x 600mm). This means the glass area is similar to a normal hatch and the greater area gives more ventilation when open. This hatch is directly above our heads when sleeping so we can see the stars. Notice also the welded tangs (with the blue rope passing through the front two) on the 4 sides of the hatch for a windscoop or canvas hatch cover.

Sorry, I don’t have a photo of the gasket side of the hatch, but I will try to take one today.

[DavidSaunders]

Thanks for your detailed and prompt response noelex.

I love that even the bare hatch under construction is beautiful. "Submarine" is a quality I am striving towards too. My old boat needs quite a bit of work before I can get there. Indeed I may never get it there, but I figure it is worth striving towards anyhow. You two and your boat are quite an inspiration.

I know epdm comes in various levels of "hardness" or "squishiness". I think I am on to the right material, I just need to figure out the compression rating system and find the material shape. 1/2" round material, so it shouldn't be too tough to find, and the right level of compression. I think the original material was neoprene, but it has degraded badly and compressed permanently so it doesn't seal well at all.

I love the thought and careful attention to detail all through your boat.
Does the glass insert simply bed into the recess in the hatch, or is there some sort of a flange/trim that helps to hold it in and seal it further?

Thanks again,
David

[noelex 77]

The hatch lens is just glued in placed, as it is on other marine hatches, but the flange is larger so the gluing surface is greater. The lens cannot be pushed inwards because of the flange so the only danger is negative pressure pushing the hatch lens out. A force from this direction is unlikely.

One problem with most marine hatches is when the hatch is opened by pushing on the handles, the hatch lens is forced outwards. As there is no flange in this direction, it is only the glue that stops the lens popping out. With time and UV, the glue breaks down and as you push up on the lens to open the hatch the glue seal starts to fail. I think this is one of the factors that contributes to leaks. The design KM has used stops this occuring. The handles are attached to the aluminium frame so opening the hatch puts no force on lens. This lack of force on the glue line should help the glue maintain its waterproof integrity.

The welded tangs around the hatches are primarly designed for windscoops etc, but these allow storm covers or boards to lashed over the hatch if the lens ever broke (the more vulnerable pilothouse windows have their own bolt on aluminium storm covers).

Having systems in place to easily deal with these problems is reassuring. It really only takes a little thought at the design stage. Some modern boats that have windows/portholes on the hull sides could, I think, particularly benefit if the manufacturers gave some attention to these issues.

Together with KM’s expertise, there has been a lot of thought and effort put into the design of the hatches, as well as into eliminating all the other possible sources of deck leaks. This may seem like overkill, but leaking salt water is the pits. The salt gets into furnishing and bedding and is nearly impossible to remove. It continues to attract moisture. Many of the posts on Cruisers Forum are about items which are nice to have, but the first priority for comfortable living on board is a dry boat with no salt water ingress, dampness or associated smells. For a boat sailing offshore this is surprisingly difficult to achieve, especially long term as the boat flexes, and sealants dry out.

The normal marine hatch can leak at the flange where the hatch is attached to deck, the multitude of bolt holes holding this frame down, the gasket on the hatch seal, the O rings around the hatch handles and where the plastic is glued to the frame. Multiply these failure points by the number of hatches, and suddenly leaking hatches are not surprising, especially given the trend to make low profile or flush hatches.

Anyway, this is a photo of the hatch seal taken today. The wideangle image gives the impression the seal is smaller than it is in reality but, it is a simple thick, flat gasket of some type of (I presume) artificial rubber, but I don’t have any more details. One the four solid stainless steel hatch handles that exerts a high compression force on the gasket can be seen. I think details such as this, which help with integrity of the seal.

[DavidSaunders]

Thanks again for your thoughtful and detailed answer. This entire thread has been amazing. I really appreciate all of your time and effort.
Merry Christmas to you both.

[noelex 77]

On another thread Steve asked about condensation on the new boat.

This is a very important subject. I have been on other boats where it was almost raining inside from condensation.

When constructing new boats, owners tend to concentrate about the number of gadgets fitted, but the first requirement of “luxury” living is quite basic. Keep the interior dry. Many boats fail this most basic requirement with deck leaks and condensation issues.

A well insulated boat makes a huge difference to condensation. If constructing a fibreglass boat, a cored structure has much better insulation than solid fibreglass, but the insulating layer is only very thin. On this boat we have a minimum of 75mm of insulation on the deck and hull above the waterline. We had this on our previous boat and it completely eliminates any condensation on the walls and ceiling. It also makes the boat very quiet in rough offshore conditions.

Unusually, we also have insulated hatches. The insulation on the hatch is thinner, but surprisingly this has eliminated any condensation on the hatch itself even during a northern winter. The stainless steel hatch handles can develop some condensation in sub zero temperatures, but the total is much less than with normal commercial hatches. The outside of the each hatch has four tie down points to allow the fitting of wind-scoops and storm covers. We anticipated making storm covers with closed cell foam to add to the hatch insulation in extreme conditions, but these have not been needed even on the hatch over the bed which has (a very thick) glass insert. Another option is adding insulation below the hatch. Many owners add bubble wrap to the inside of their hatches, but with the built in insulation incorporated in our hatches, this is unnecessary.

The next step in reducing condensation is eliminating any bilge water. A dry bilge is a fantastic help. This was the major reason why we elected to go for a deck rather than a keel stepped mast.

Heating and ventilation are the keys to reducing moisture in the interior. Here the Reflex stove is a great dry heat source. The Reflex also allows for cooking without using propane. Propane/butane introduces a great deal of water vapour. Ventilation is also critical. We left out the traditional dorade vents, as our experience has been unless these are very large they do not work well.

Our companionway can be left open or partially open as it protected from rain by an aluminium doghouse. Stainless steel security bars mean the companionway can also be left open when leaving the boat, if this is needed, although this feature is more for hot rather than cold/wet weather. We also have hatches in the shower and in the toilet that can be left open for cross ventilation. With the addition of a rain cover (using the four external tie down points) these remain dry at anchor. Security bars mean the hatches can also left open when leaving the boat.

Pilothouse windows. This was the area we made the most compromise to condensation. Double glazed windows are an attractive option to reduce condensation, however in the marine environment unfortunately there is a risk of moisture becoming trapped between the two layers. This requires replacement of the window. In the spirit of KISS, we elected to stay with single layer windows and externally had tapped screw threads added around them. These are primarily for aluminium storm covers that can be attached if a window breaks, but they can also be used to attach shade cloth or a separate perspex layer, creating a temporary double glazed window if required. So far our other steps taken to eliminate condensation mean the pilothouse windows have stayed condensation free without any perspex covers, but this provision was easy to add during the build stage and as noted above, it has multiple purposes.

Apologies for the long post. I seem to have written an essay on condensation , but this is an incredibly important subject if you want to be comfortable and still be able to cruise all locations, especially without shore power (which allows for electric heating and dehumidifiers).

[De.windhoos]

Originally Posted by noelex 77

Heating and ventilation are the keys to reducing moisture in the interior. Here the Reflex stove is a great dry heat source. The Reflex also allows for cooking without using propane. Propane/butane introduces a great deal of water vapour. Ventilation is also critical. We left out the traditional dorade vents, as our experience has been unless these are very large they do not work well.

Noelex, you have way more experience than me, but I'm always confused by the "Propane introduces water vapour when cooking" argument. I mean doesn't the act of cooking itself add much more water vapour than the stove itself?

[Juho]

Thanks for the update on cold weather performance and condensation. I'm very interested to hear your experiences on that now when you are sailing in cold climate, especially since I mostly sail in the northern latitudes.

I'm happy to hear that the 75mm insulation layer and the insulated hatches are sufficient to eliminate almost all condensation. You said that the hatch handles develop some minor condensation. How about the metal frame of the hatch?

The pilot house windows are high up in the cabin and may lose a lot of heat in cold weather, in addition to being a potential source of condensation. I might consider some curtains or other insulating sheets that could be inserted inside when you don't need the visibility. It is anyway a fact that the roof and other places high up in the cabin are the place where you lose most of the heat. Another interesting spot high up in the cabin is the companionway. Is it insulated and airtight?

One more thing that I might consider is a heat exchanger. That would allow you to continuously ventilate the cabin without losing too much heat. Do you have one or would that be worth considering? It would work both in cold climate and in the tropics.

[Sailmonkey]

Originally Posted by De.windhoos

Noelex, you have way more experience than me, but I'm always confused by the "Propane introduces water vapour when cooking" argument. I mean doesn't the act of cooking itself add much more water vapour than the stove itself?

Burning propane release a ton of water vapor as a byproduct of combustion. Almost as much as heating a pot of water to a boil.

[john61ct]

1.64 pounds of water per gallon of propane used

Added to that produced by cooking

Plus the large amounts just from mammals living within the space.

Hence ventilation needed as well as active and vented-combustion heating.

[GordMay]

4 moles of water are produced from each mole of propane burnt, so multiplying by 4 gives the number of moles of water produced per unit of time. So, if you have complete combustion of propane, you will produce 4 cubic feet of water vapour, for every cubic foot of propane burnt.