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Thread: 8M dual outboard setup?

  1. #1
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    Default 8M dual outboard setup?

    Hi All,

    For those who are able to read french, on this thread @ hisse-et-oh I read the post from Guillemot mentioning an English 8M owner having his Catalac equipped with dual 4-stroke 5 hp outboards...

    Does this owner happen to be on here? Somebody knows more about this setup?
    I wondered about the dual outboard setup possibility some time ago so talking to someone who has this setup would be nice...
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  2. #2

    Default Re: 8M dual outboard setup?

    Hi Djeeke,

    I know a guy, he owns a catalac 9m named Panthera, located in Preveza, Greece. He uses 15hp outbords, a mercury and a mariner, but they are quite similar, he told me he can go 7-8 knots with both and 5,5-6 with one engine running. We didnt talk about consumption.

  3. #3
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    Default Re: 8M dual outboard setup?

    Thx Squib,

    From talking to the OP on the french forum I understood that the owners of that 8M went through the involved (complex) work to install the engines in outboard wells inside the rear cockpit lockers so positioning the props approximately where the props of an inboard would be...
    I agree this puts the water flow over the rudders and keeps the props well in the water but this whole process seems a lot of work...

    I was wondering about the dual 5hp on the 8M, to me this sounds on the low side knowing the original single outboard was a 25hp and the inboards were twin 9hp Diesels (got this from the catalac product brochure).
    I know it's not all about hp, props are important as well. I currently have a Mercury F15EL outboard and am sure a 9.9 Yamaha High thrust would do a better job...

    You mention dual 15's on the 9M, in my mind this sounds closer to the original outboard power.

    Also I wonder about weight of the used outboards, do you know if the 15 hp's are 2 stroke or 4 stroke outboards? (my 4 stroke F15EL weighs well over 50kg - 2 strokes were a lot lighter)

    Do you happen to remember where he has the outboards installed?

    As the 9M has the extended platform astern I wondered about this and went through my archives on the 9M...
    I found a few pictures of 'Magic Carpet' with twin 35hp Mercury outboards: platform cut-out and transom hung...

    Sorry no better pic...
    Twin 35's ??? talking about overkill !!!
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  4. #4

    Default Re: 8M dual outboard setup?

    Hi,Djeeke
    i was mot so interested in the mounting, but what I saw was that the engines have been mounted in the rear cockpit lockers and the engines have been used 2-strokes, I don`t know the weight of them. From outside it looked that the props are on the same position as mine with the inbord diesels. my engines are very close to the front of the front cockpit lockers, to change the impellers I have two flaps inside the head and the aft cabin to get acess. If you are interested, I can take some pictures, end of July when I am in greece again and Panthera is on the hard. In the ionian there are some catalacs around, I know 6 of them.

    Peter

  5. #5
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    Default Re: 8M dual outboard setup?

    Thx Peter,

    Mounted in the lockers so props are in the same position as with an inboard engine, sounds like the same setup as the 8M with the 5hp 4-stroke outboards...
    I never ran into catalacs with dual outboards before so it's interesting to see at least 2 of them have a similar setup with the outboard engines mounted inside the lockers...

    I am considering a dual outboard setup. I am not paranoid but I love the idea of redundancy, I have seen engine failures before (even dual engine failure on a cat)...

    If you could take a few pictures, sounds great, this way I can visualise how they have been installed
    Last edited by djeeke; 18th July 2017 at 01:03 PM. Reason: typo
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  6. #6

    Default Re: 8M dual outboard setup?

    Hi, Djeeke,
    I will see what I can do for you, but its not my boat, i have to ask the owner to get access.
    Why do you don`t think about diesels, they consume less and the fuel is saver than gas. I am thinking about one diesel and one electric engine, if one of my diesel dies. I want to build a hardtop over the cockpit, much place for solarpaneels and some more on the gantry, but now both are running and i am very happy about this.

    Peter

  7. #7
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    Default Re: 8M dual outboard setup?

    Hi Peter,

    I know it's not your boat, any info would be nice, if not, no worries
    I have asked more info to the guy on the french forum as well, again it's not the poster's boat but he would also ask info if he runs into the 8M again (which apparently he does sporadically) and/or put me in contact with the owners...

    Diesel vs gas debate on safety is another one, I would install the gas tanks in the wet lockers, no gas or even fumes ever inside the boat as they are always well vented...

    I am interested to see how the outboards are mounted inside the lockers (fixed or can they lift out of the water?) but my initial idea is to mount long shafts next to the rudders, there are pro's and cons to this setup:
    - might lift clear of water in heavy seaway
    + keep the option to connect to rudder and steer with the engine so even on one engine manoeuvres should be possible.
    + could be installed to lift clear of the water when sailing (no fouling)
    + no fuel lines inside the boat (tank in wet locker close to the engine)
    + minimal loss of locker space (fuel tanks)
    - easy access for those who love my outboards and want to 'borrow' them without my approval
    + same as above to take the engine to a shop if repairs are required

    Anybody, please feel free to add/comment on this

    <off topic>Why would I not go for inboard diesels?
    - Budget: no clue what the budget would be to install two inboard diesels, engines, drive shafts, propellers + installation costs... I need to compare this to two new 4stroke or second hand 2/4 stroke outboards and installation. But as I am inclined (weight on transom) to go to 2-stroke I think the difference in budget will let me run many many hours on gas even it the engines drink more than an inboard diesel...
    - Locker space: As you know the diesels take up some locker space... I guess you are clear of diesel smells inside the boat as they are in the cockpit lockers but I've been on cats where they are under the aft berths... (and since I'm a candidate for seasickness I assure you this is not a positive)
    - Weight - Not a personal negative to me but some would say weight is in the game, not sure what the weight of inboards is... Probably double of outboards... My current Mercury F15EL 4-stroke is around 55kg... Going to two strokes, Yamaha 8hp is around 30kg, 9.9/15hp (basically the same engine) is around 40kg...
    <on topic>

    Electric, has been on my mind as well, here again there are a few options, some on topic, some off topic...
    - Mount a shaft with a prop and DIY install an electric motor on it.
    - Fixed pod under he boat (like the torqueedo Cruise 4.0 FP).
    - Electric outboard (like the torqueedo Cruise 4.0 RL).
    - DIY electric outboard: get a scrap outboard, replace the ICE engine with an electric motor... (cheapest but also least effective due to additional losses in transmisson which you don't have with direct drive)

    (I guess your best options if one of your diesels fails and you want to replace it with electric are option 1 or 2)

    The big question is range vs battery banks and a way to keep these charged... If you need lots of capacity, lead/acid batteries are heavy and expensive (wen you need a whole bunch of them), newer technology batteries are much lighter but also cost a lot more...
    Your diesel can deliver some charging capacity and I guess could even be equipped with a second alternator (you could save the one from the broken engine )
    Mix gas/electric outboard does not have this luxury, outboards just don't deliver any real battery charging power...
    Yes solar helps, it all depends on your usage if you need electric drive for some distance every day there is no way solar can keep up, if you only need to motor 10 minutes before the sails go up you could be fine...

    I still have a lot of work on my 8M so for now I'm not even considering electric right now, budget and timewise (to work out a suitable DIY electric outboard setup) there is no room...

    Yes a hardtop over the cockpit will give you space for solar panels, keep in mind some might get shading from mast/boom...
    I am considering the build of a rear arch to install a few solar panels.. (another project that will require lots of thinking before executing but I guess this is good for a new separate topic)
    Obviously you can fit a lot more panels on a hardtop...
    <off topic>I think we have different weather over here, my preference would be to install a full tent over the cockpit (didn't I mention there still is a lot of work on my 8M). Yet another project I need to think about budget and timewise...
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  8. #8
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    Default Re: 8M dual outboard setup?

    As it seems I've shared too much on photobucket and I can not edit my posting above...
    The 9M with two outboards
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  9. #9
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    Default Re: 8M dual outboard setup?

    The dual outboard alternative I have in my mind to dual inboards (wether diesels on driveshafts or outboards in wells) is to mount dual outboards next to the rudders...
    Where would you mount them and why?
    * outside of the rudders which spaces the engines far apart like the position used here on Lady Lyne:


    * Inside of the rudders as here on Banana Split:


    And what type of mount would you use? I am personally in favour of the slide type mount as used above on "Banana Split" but have personally not yet seen or read a comparison between both setups...
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  10. #10

    Default Re: 8M dual outboard setup?

    There is a catamaran I have looked around, an 8m that has 3 outboard engines. One is a 9HP 2 stroke mounted centrally and the other two are Tohatsu 6HP saildrive ultra long shaft motors. The two 6HP's are each mounted in the end of the cockpit lockers inboard on the rudders (meant losing about half of these lockers). There was substantial GRP work involved but the whole thing looked pretty good. They lifted up and down as did the central engine. This same boat was an 8M but had the sliding hatch area and forward of that cut out as is the 900. The owner (was from Chrsitchuch and knew a lot about Catalacs and knew John Lack) had never noticed any flexing of the structure having the full standing head area by the table. That would make sense as this is only about 2ft x 5ft, over and above the hatch. The boat was called Me 'N Er but not seen it or the owner since.

  11. #11
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    Default Re: 8M dual outboard setup?

    Hi Keith,

    Interesting to read we could cut out the portion of the cabintop above the salon... Just confirms they are very strong boats!

    2 outboard wells inside the cockpit lockers, seems like there are at least 2 8M's where this work has been done, the one you mentioned and the one mentioned on the french forum as well as 1 9M, Panthera, mentioned by Peter....

    If I am able to obtain more details I will mention them here, personally I do not think I will go through the extensive GPR work of constructing 2 wells in my 8M. No way I am moving my 4-stroke 15hp Mercury to the transom, it's way to heavy! So either I keep the current 15hp central outboard and ad a smaller (lighter) one on the transom for redundancy purposes, either have two similar ones on both transoms. I'm not in a hurry...
    1979 Catalac 8M - 8-84 - Galu'Lati Go

  12. #12
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    Default Re: 8M dual outboard setup?

    You can trace the catalac back to the bobcat. If you get the the catamaran cruising association website http://www.catamarancruising.org/ you can look through the pdf's to find pictures of how the originals were rigged with dual outboards. Considering the same type of hull shape in a catalac one would assume a dual outboard setup should go between the hulls away from the rudders.

    Of course that is the limitation with the existing outboard well smack in the middle of the cockpit. We find that on the bobcat it does work and is only one of the places that does allow for correct steering of this type of cat with no rudders.

    In our case it was the design criteria we were after. Even though we had a new extrusion and sails available we opted to not go that way for ease of use and simplicity. The cons far outweighed the pros in the matter. We ended up with a completely solar electric catamaran that gets the same performance or better with none of the sailing problems and we get most everything we can from our solar installation 2160 Watts..

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