Catamaran conversion

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  • 08 Apr 2022 23:23
    Reply # 12700613 on 12688183
    Anonymous member (Administrator)

    It struck me, and appealed to me personally, as potentially a comfortable proposition for a retirement living aboard motor sailer for cruising inland waterways and sheltered coastal waters. But less so, perhaps, for being based in Portugal .and accessing the North Atlantic.

    Good luck in your search, I imagine there are many good opportunities out there at the moment.


    Last modified: 08 Apr 2022 23:41 | Anonymous member (Administrator)
  • 08 Apr 2022 20:54
    Reply # 12700418 on 12688183

    I think I might have to let this one go for now. I want to thank you all for your very valuable advice.

    I've contacted 4 different respectable boat builders in The Netherlands and they don't want to touch this. The only thing I have asked from them so far is to build the tabernacle and give me advice on how/where to reinforce the structure. None of them believes it can be done or wants to take it on. It might have something to do with being home-built or the unstayed mast.

    The listing agent answered my questions. Sailing characteristics are not very clear, there wasn't enough wind to test everything. Most worrisome is the answer to my question about the bulkhead dividing the engine and lateral bunk, supporting the current mast.

    Supposedly none of the bulkheads have been glassed into the super structure but instead there is a framework of beams supported by stainless brackets. The bulkheads are just dividers that don't supply much rigidity to the vessel. Also it is unclear if the bridge deck is sandwich or solid.

    I don't think a hybrid solution would do it because there is just no way towards a full unstayed JR (I would entertain the hybrid temporarily if possible)

    Again, thank you all for your help. I will be able to use all this information as soon as I find a more suitable vessel. Or maybe I might change my mind. I do plan to visit the area in early June, I might have a look at the vessel then. I will keep you posted.

  • 07 Apr 2022 14:25
    Reply # 12698228 on 12697627
    Anonymous wrote:

    I've never had hydraulic steering but all the ones I have seen do not need the motor to be running, or any electrical power. The pump is usually just part of or driven by the wheel hub. You turn the wheel - that displaces some oil - which in turn pushes a ram. That's it. Maybe Howard is thinking of power steering, but there'd be no need for that.

    The diaphragm or bulkhead is 2-dimensional and if it doubled up that firewall in front of the motor it shouldn't take up much of the accommodation I would have thought. The heel  of the tabernacle needs to be on something solid and  fixed, and even better if it could be integral with the athwartships diaphragm. The mast needs to be secured in the tabernacle so it can't rotate (junk rig puts a rotational force on the masthead crane, and masts have been known to rotate as a result). The partners at the deckhead need to be substantial. Annie on her FanShi arranged her tabernacle so the mast heel was in the tabernacle at, or just above, deck level, making a permanent 100% watertight installation at the deck - a good idea if that leaves you with enough bury of the mast in the tabernacle. The height of the deckhouse that you need to clear makes it look as though this would be an obvious option for you. If you are building a new tabernacle for an aluminium mast (or any mast, really) the traditional pin-thru-the-mast at its most critical point is a poor detail for a free-standing arrangement, and there probably are better ways, so keep that in mind when the time comes.

    These well-meant forum posts are just general ideas and necessarily a little bit speculative. I didn't realise, you are obviously well placed to get good local professional boatbuilding advice and/or service, so I think the best advice is that you take advantage of that for all your structural questions. 

    That "diaphragm" will need to be structural, strongly fastened to a deck beam and the bridge deck. What is there currently may only be a partition or a firewall. You can maybe double it up with another heavy layer  but it needs to be connected strongly to partners and the bridge deck and/or other structures to carry much more lateral force than the current stayed rig requires. Have a good look at that.

    Good luck if you go ahead with it, and be sure to report on progress.

     

    There was a mistaken communication.........My comment was about hydraulic autopilot rather than hydraulic steering.  Actual hydraulic steering does not normally require power.   On anything but a short sail, autopilot is pretty important for most folks......  Who wants to be locked down to the wheel for many hours? 


    There appears not to be any significant keel....... The description is "keelson" and skeg, both of which are visible in one photo.......  The keelson looks  like it extends most of the length, but .......is just that, nothing that really qualifies as a keel.  A dark structure (fence?) behind in the photo does not make it easy to discern what is there but it looks like essentially  nothing.   I've played with contrast, etc, but the shades are close enough that you cannot really separate things except with a careful visual examination.  At first glance it appears to have an actual keel........ looking more closely, it actually does not.

          Note that I was wrong about the structural H, having assumed the berth to be a "child berth".  It was clear that the longitudinal bulkhead shown at the washstand was not on center, and not structural...... I simply assumed that there was some sort of stowage area.  I like Ivan's idea of using this berth as an office desk space or nav station, or whatever and developing the existing beam leaving a stowage space behind. That combined with the main structural bulkhead forward of the engine would create a strong intersection for the base of the tabernacle to rest on, and to transmit the lateral and longitudinal loads of the tabernacle base.   The upper support will be more of a challenge I think.

    2 files
    Last modified: 07 Apr 2022 16:01 | Anonymous member
  • 07 Apr 2022 10:48
    Reply # 12698013 on 12688183

    This is boat is lying very near to where I live, that is right.

    Someone I know was looking for a cat and visited this one. He was put off by the engine on the bridge deck which is noisy and the rig not being a 'sailing rig'.

     Not sure about the condition of the boat though. 

    Let me know if I can help.

    Regards Rudolf


  • 07 Apr 2022 02:20
    Reply # 12697627 on 12688183
    Anonymous member (Administrator)

    I've never had hydraulic steering but all the ones I have seen do not need the motor to be running, or any electrical power. The pump is usually just part of or driven by the wheel hub. You turn the wheel - that displaces some oil - which in turn pushes a ram. That's it. Maybe Howard is thinking of power steering, but there'd be no need for that.

    The diaphragm or bulkhead is 2-dimensional and if it doubled up that firewall in front of the motor it shouldn't take up much of the accommodation I would have thought. The heel  of the tabernacle needs to be on something solid and  fixed, and even better if it could be integral with the athwartships diaphragm. The mast needs to be secured in the tabernacle so it can't rotate (junk rig puts a rotational force on the masthead crane, and masts have been known to rotate as a result). The partners at the deckhead need to be substantial. Annie on her FanShi arranged her tabernacle so the mast heel was in the tabernacle at, or just above, deck level, making a permanent 100% watertight installation at the deck - a good idea if that leaves you with enough bury of the mast in the tabernacle. The height of the deckhouse that you need to clear makes it look as though this would be an obvious option for you. If you are building a new tabernacle for an aluminium mast (or any mast, really) the traditional pin-thru-the-mast at its most critical point is a poor detail for a free-standing arrangement, and there probably are better ways, so keep that in mind when the time comes.

    These well-meant forum posts are just general ideas and necessarily a little bit speculative. I didn't realise, you are obviously well placed to get good local professional boatbuilding advice and/or service, so I think the best advice is that you take advantage of that for all your structural questions. 

    That "diaphragm" will need to be structural, strongly fastened to a deck beam and the bridge deck. What is there currently may only be a partition or a firewall. You can maybe double it up with another heavy layer  but it needs to be connected strongly to partners and the bridge deck and/or other structures to carry much more lateral force than the current stayed rig requires. Have a good look at that.

    Good luck if you go ahead with it, and be sure to report on progress.

    Last modified: 07 Apr 2022 07:12 | Anonymous member (Administrator)
  • 06 Apr 2022 22:56
    Reply # 12697335 on 12688183

    Thank you Graeme, your idea to put the mast behind the engine is exactly what I have been dabbling with in my mind. Howard also e-mailed me privately with similar thoughts.

    Going by the photos. There is a lateral berth behind that bulkhead that I would probably turn into storage. Behind this berth in the opposite hull currently is a wash basin. See attached photos of both 'ends'.

    https://www.multihull.nl/multihulls/used-multihulls/78203.westerloo10m/78203-ps-double-centre.jpg

    Above photo shows a 'beam' in ceiling at what I assume is the center line of the vessel. I was thinking of reinforcing this beam with another dividing bulkhead smack on the center line, and build the tabernacle buried inside this construction. Your proposed 'diaphragm' is already present and visible in above photo to the right (=aft)

    https://www.multihull.nl/multihulls/used-multihulls/78203.westerloo10m/78203-vanity.jpg

    Above photo shows the opposite hull same location of the lateral berth, the mirror is hanging on the backside of the 'headboard'

    I think this could create a large storage area behind the mirror (accessible via a door) and on the other side I would mimic this configuration to create a desk/work area.

    On the question of what I would use the catamaran for. My wife and I would live aboard part time (up to 6 months per year) while we slowly bring it to the Med (We are moving to Portugal in a couple of weeks). For the first season, the boat would remain in Friesland for the conversion. I grew up in Friesland, I speak the language(s) and I have family and friends close by. The tabernacle is meant to make it easy to service the mast, I don't intend to travel canals or low bridges (but one never knows)

    Howard pointed out this vessel has hydraulic steering which will require a lot of electrical power (or I would have to run the engine all the time) There seems to be something up with the waterline as the boat is sitting really high up on the water. It looks like it is completely empty and the specifications say it has only 600kg of displacement weight left. I worry I will overload this catamaran when we live aboard (which is a common problem with multihulls)



    Last modified: 06 Apr 2022 22:57 | Anonymous member
  • 06 Apr 2022 04:22
    Reply # 12695982 on 12688183
    Anonymous member (Administrator)

    0.8m draft, long keel displacement catamaran, possibly deep vee, probably symmetrical hulls. Possibly up to 14 sq m of lateral plane.I'll be very surprised if it won't go to windward. Not spectacular perhaps - a lot of windage in that superstructure, yes, but don't give up on that aspect yet.

    Solid glass, timber cross beams and sandwich deck (cabin top). 

    1oohp diesel engine engine mounted east/west just behind the tabernacle. There ought to be heaps of structure there to tie a sunk tabernacle into but unfortunately no photo to show. Best case scenario you might just need to beef up what is already there, ideally a diaphragm between (but not necessarily including) the two hulls, bounded top and bottom by, and fastened to a cabin top beam and a bridge deck beam, located perhaps between the engine and the mast (tabernacle) support. (about where that fire wall is on the fuel-pump side of the motor).



    (If no standing rigging then a diaphragm or bulkhead  the width of the bridgedeck might be enough,  bulkhead probably need not extend right out to chainplates, which won't be used, diaphragm as shown (structural bulkhead) between bridgedeck beam and cabin top beam might be enough). Some fore-and aft structure might be needed at the cabin top (partners). Fastenings need to go through solid parts of the cabin top. (There must be some solid parts there ylou can use, especially at the existing tabernacle which won't be just sitting on a sandwich). The above is assuming you want a sunk tabernacle, and above deck free-standing mast. I think this is along the same lines as what Howard is saying referring to his "current position of mast" option.

    If you were to follow Arne's suggestion and have a simple 3-stays-to-top-of-mast arrangement you might not have to make any changes at all, subject to taking a long hard look at that pin-thru-the-mast tabernacle which is not what I thought it was, but that's a subject for later.

    That's just my view of it. Best get a boat builder on the spot to look at it and assess.

    I sent an email to one of our members who is based in Friesland, you never know your luck, he might know the boat or how to find the builder.


    An afterthought - I see the mizen mast is in a tabernacle too. Maybe the whole set up is designed to revolve around easily lowered masts - for canals and bridges? Maybe the rig and power setup is optimised for canal cruising? If so and that's your intention why change anything? Our member in Friesland is Rudolf, his boat is De Skou which was featured on the website homepage (go to featured boat archive here and scroll down to June 2020)


    Last modified: 07 Apr 2022 02:38 | Anonymous member (Administrator)
  • 05 Apr 2022 16:01
    Reply # 12694791 on 12688183

    Graeme, Howard and Arne,

    these are again great tips and super helpful information.

    As to the hulls being solid glass, here is the english description from the listing:

    This comfortable cruising catamaran is designed by the builder himself to meet his requirements, that he couldn't find in other catamaran designs. The yacht is built inside a female mould in solid GRP with sandwich decks. Despite the sturdy cabin the sleek hulls slice through the water quite easily, giving pleasant cruising speeds, thanks also to the relatively low weight. The term Motorsailor is derived from  the double wheel stands, inside and out in the cockpit, the powerful Mercedes diesel engine that drives two propellors and the modest, easily handled ketch cutterrig with lowering masts. The accommodation is simple but comfortably finished. She can be viewed in Friesland.

    Here is the link to the listing if anyone is interested to see many more photos and there are also the specs: https://www.multihull.nl/multihulls/used-multihulls/78203.westerloo10m/10m-motorsailor-description.html

    I tried researching Westerloo catamaran designs but I haven't found anything so far.

    I am still waiting to hear back from the agent, I have begun a second list of questions while I started reading the thread on Moon Run's conversion. It looks like I also need to find out how strong and in what manner the bulk head under the original mast location has been constructed. Personally I am worried about the state of the decks, hopefully they are not soft.

  • 05 Apr 2022 05:51
    Reply # 12694217 on 12688183
    Anonymous member (Administrator)

    Getting the horse in front of the cart

    Hats off to Howard for taking so much trouble to analyse the photos and start discussing structural ways and means. Of course, I am in no position than to do other than approve of the post being “long winded”. And I happen to agree that the most promising direction to go in, with the little we actually know, is to try to utilise the existing mast position because it looks as though that might well be possible. However, I think it is a little too soon to get too far ahead, just as it is too soon really to be speculating about type of junk rig, number of masts, whether or not a tabernacle, high or low aspect ratio etc. We don’t even know yet for sure what the hulls are made from.

    I think it is sufficient at this stage to look, in general terms, at the issues these things raise, especially mast location and how it affects plan form. And how in turn it is affected by structural and accommodation layout. As an aside, Arne’s suggested sail plan has huge merit for consideration and is valuable for general discussion.

    Where does this leave Ivan now? Better informed, I hope, regarding the research he now needs to do and the options which may be available to him.

    Ivan writes: “I am waiting to hear back about sailing characteristics and a floor plan” and I think that’s a good start and about as far as anyone can go for the moment. “Sailing characteristics” will need to include some details of the hull form and any appendages below the water line, and preferably also the designer's sail plan. “Floor plan” will best include structural details, not just layout of berths, galley etc.  

    I have little doubt that one way or another, this boat could be satisfactorily converted to a suitable junk rig of some kind.  I agree with Howard, that question can be considered as answered. The technical knowledge needed to tackle the project can be acquired as the project is rolled out – I am all for that.

    But I still remain slightly uncomfortable with the fact that a certain amount of technical knowledge will be needed right now, in order to assess this vessel and decide how big and how much of a commitment the project is going to be. That’s where I tend to get tripped up. That's where I think Ivan needs help at this particular moment, and not being on the spot, the people who are willing and able to help will need more information than some photos, a floor plan and a statement from the agent as to its sailing characteristics.

    All this presupposes that the boat has been surveyed or competently assessed and that it has a clean bill of health in its current state. Ivan: get it surveyed or assessed and make sure your proposed investment would be safe. If you seek technical advice on a junk rig conversion, insist that the agent identify the design and obtain the structural drawings and/or put you in contact with the builder, so that the necessary information is available to experts who are not on the spot.

    PS Ivan, it hasn't yet been positively asserted that the hulls are solid glass (it has a bit of a "glass over ply" look to me, but it is ridiculous to speculate). Scoping these structural details, as you are doing, is a good direction for the discussion to go in now, I think. It will be interesting to get some more factual information and I do hope you can get hold of the builder and/or designer and dig out some more factual information.

    (Should the hulls prove to be of solid fibreglass there are other threads on this forum which have taken us through the details of prepping and grafting in new bulkheads and other structures where needed - the hard part is trawling through the technical section of the forum and finding them. Scott's Moon River thread comes to mind as an example - it starts here and its worth starting at the beginning.

    Hopefully such major changes won't be needed). 

    Junk rig is a means to an end, it shouldn’t be an end in itself. If the boat is sound and you like it very much, you will be happy with it even with its existing ketch rig. A season or so will give you time to get to know the boat, get lots of good advice – and the junk conversion can happily evolve in due course.


    Last modified: 05 Apr 2022 06:02 | Anonymous member (Administrator)
  • 04 Apr 2022 14:47
    Reply # 12693259 on 12688183

     Pardon my long winded post....

         Again........ my opinion is not based on any experience doing any junk rig conversion, only on my experience with structural engineering in general so should be taken with LOTS of salt (water?).    Below are my observations and conclusions looking at the various photos.  I believe that this boat could realistically be converted to a single mast junk rig, and that this is the single mast in close to original location would be the most desirable from what we can see........ which is not much.   That  location would be my initial focus if it were my project based on what I can see.  It also corresponds with some of the proposed sail plans that seem the best options.

    Note that in the most recent photos some tentative conclusions can be reached about the structure for mast placement.  In the first photo port side, you can see the bulkhead marked with red which has a chain plate strap bolted to it. You can see what is presumably the master berth forward of it, and another berth aft of it which does not extend all the way across as the head is on the opposite side.  The marked bulkhead looks like a very substantial bulkhead that both has a structural function, and provides privacy between the berths.  That berth aft of the master probably only extends to the center of the bridge deck, and you can see that the head countertop also extends inward.   The second photo starboard side shows the head, and also shows a bulkhead forward of the one marked in the previous photo, obviously also a major structural bulkhead, also with a chainplate strap bolted to it.   This forward of the two bulkheads is the one the mast step rests on apparently.   Looking at the window locations , interestingly the chain plates on deck do not correspond to the chain plate straps seen inside.... which is interesting, and suggests some significantly strong longitudinal member concealed inside the hull side, but what is clear is that the originally selected location to relocated the mast forward of the two hatches on deck is well forward of the marked bulkhead, and has minimal structure....... no bulkhead, just a light beam that may be seen in the ceiling of the master berth where it begins to slope downward.   The photos suggest that the selected bulkhead is about half way between the original mast location and the first selected location to relocate the mast.   The photos lead me to draw the conclusion that most likely there is an H structure of bulkheads.   These two long ones extending across the boat and a shorter one joining them, probably also fairl substantial, the juncton being the location of the mast step, and the entirety being a major structural element joining the two hulls and forcing them to move as one.

           To me that means that there are two possible locations for the free standing mast.  One at the forward junction of this H and the other at the aft junction where it currently is.  

          It is also clear that a keel stepped biplane rig is out of the question, as it would ruin the interior accommodations.   which means that a "creative" setup such as was used on Alleda would be the only realistic biplane rig option.

           The chainplate structure seem to me as was suggested could be used to help support a tabernacle at either the original location or at the forward location............but loading on the chain plates structure if this were the only support would be many times higher than original due to simple leverage.  The tabernacle should have metal structure extending all the way through the deck to the bridge deck and bolted into the bulkheads used, which probably need to be reinforced to distribute the side to side and forward and aft loading.  Structurally the ideal location would seem to be the original mast location, or even slightly aft of it as one drawing in an earlier post showed.   This would presumably provide the cabin top as an additional structural element to carry mast loads.  It might need some creative reinforcing......... perhaps unidirectional carbon fiber, etc.  It would be the least visually offensive as well as the most practical IMHO.   Looking at the various proposed sail plans.


                                                    H.W.


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    Last modified: 04 Apr 2022 14:51 | Anonymous member
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