Tenders stored on foredeck

Discussion in 'Boat Design' started by sabahcat, Nov 23, 2010.

  1. michael pierzga
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    michael pierzga Senior Member

    Pulled the tube off the bow, then she was a gonner ..Dive Dive Dive
     
  2. Stumble
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    Stumble Senior Member

    RH,

    We had a great system on the last sailboat. We used a 13' ridgid bottom inflatable with a 30hp outboard. Took one heck of a beating over the years, and other than engine problems never had a problem with it.

    For storage we had a platform bolted to tracks on the stern. While underway the boat rode at above deck level, and when the platform was down it doubled as a swim platform. One of the nice things is that in questionable anchorages the dinghy could easily be raised out of the water so theft wasn't a concern.

    I am looking for some pictures, but don't have any handy. Something like a 2 piling boat lift http://www.boatliftdistributors.com....-2-Piling-Mount-(Aluminum)/product_info.html but mounted on either side of the transom.
     
  3. michael pierzga
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    michael pierzga Senior Member

    Those lift systems are OK, but difficult to use. A bit of seaway and everything is bouncing around. If there is any stream you have to physically manhandle the tender "beam to " the wind and stream to load it. . Many times The tender diver has to stay in the tender while loading...unloading is also a hassle. Makes single handed tender retrival a nightmare. Id prefer well thought out davits. The gold standard is bow forward , pull into the yacht, tender retrieval. Same with launch. just let her go with a long painter attached. Difficult to achieve on a small yacht. Oh and a 30 hp outboard is much to big for a tender. stay 10 hp or under.
     
  4. sabahcat
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    sabahcat Senior Member

    Picture of one in post 10
     
  5. Stumble
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    Stumble Senior Member

    Not when carrying 6 people with dive gear.


    In 10 years of cruising we never had a problem performing this operation singlehanded. With the exception of +40kn of breeze it was always a solo operation, and while most of the time I did the lift from inside the boat, that was just because I was lazy, and didn't want to climb out first. After about 2 hours of sizing dock lines to fit holding the dinghy wasn't a problem.
     
  6. michael pierzga
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    michael pierzga Senior Member

    I cant believe that in ten years you never had problems with the platform arrangement in a seaway. I have a platform and it is awash many times. many times rib retrieval is so difficult that I tow the rib until I can find a quite bay or shoreline , then haul or launch. At present my rib has substantil bruising and hard knocks on its bottom from banging the platform in a seaway

    Of course when you are operating industrially you may have any power you like...30hp is not a tender.......And again 30 hp is too big. Fuel use....fuel is dangerous to store and your insurance company will not be happy. Weight...tender becomes too heavy for single handed beach handling. Weight again...heavy motors affect the floatation on a Rib and as a result you loose the self bailing feature of a Rib...always wet feet when you jump in. And lastly..most countries in the world in which you will operate restrict a tender to 10hp...above ten hp and the operator must hold a license. Difficult for a cruiser to make sure that every crew guest is licensed.
     
  7. brian eiland
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    brian eiland Senior Member

    Core Material Question

    How does that core material compare with Nida-core??....or is it the Chinese version of nida-core? Just wondering
     
  8. brian eiland
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    brian eiland Senior Member

    Rigid Inflatable Boat Proposal

    ...a cover ltr I sent to a few persons several yearrs ago....thought there might be some interest

    Over the past few years I have been conceptionalizing a small RIB (Rigid Inflatable Boat) tender for the use on cruising sail and power vessels, and sportfishing vessels in particular. It would put emphasis on a number of enhanced features that I do not believe are adequately addressed in the current market. I had written briefly on two previous occasions:

    1) I was searching for a short, wide, open-transom tender/dive/sport craft that could be carried on the front deck of a gamefishing catamaran of my design (preferable two such tenders). I was seeking a relatively small craft that comfortable could carry 4/5 persons with some dive and/or dive/fishing gear. Too many of the existing RIBs are too confining in their interior space, particularly with their big round tubes. I wanted two persons to be able to sit on the tubes directly across from one another, and yet still have the leg-room and passage room to clear a central straddle-seat that might house a jet-ski type power plant. That would necessitate a fairly wide craft with a central hull that could house the water-jet drive unit. A wide craft needing a central hull rules out the cat configuration. I could have a transom for its structural contribution, but it needs to be ‘open’ to allow for immediate evacuation of any water that might swamp it as a result of a large wave washing over the bow stowage area of the mothership. With width I could accommodate the people without excessive length, and thus keep the boat size small and light-weight for the continuous hoisting service it will experience.

    2) To another party I had written, “you chose to build your own tender. I have one in mind myself. It would be a RIB, possible with a foam collar rather than inflatable tubes. It would be virtually transom-less, or at least maybe just a rigid frame at the transom. The purpose being it would totally self-bail in an instant when subject to a big wave, and particularly when stored on the bow as with many sportfish vessels. It would be ‘extra wide’ for its length for increased capacity and ‘across the aisle seating’. It would have a modified ‘tri-hull’ bottom akin to XXXXX for superior performance in a chop as opposed to shallow deadrise of a very wide deep-vee. It would have a central saddle seat that would cover an optional inboard jet-ski style engine in lieu of a traditional thief-prone outboard….also safer no-prop diving usage. Ultra light model in carbon fiber, traditional model in stamped ABS.”

    I made a trip to the Miami boat show this Feb 06, and I was disappointed again. As I look thru the market I’m not finding a RIB tender/sportboat that could be carried on deck, or in davits, that is really ‘self draining’. They all appear as a captive ‘tub’, that if flooded by a random wave would become a very heavy ‘big bucket’ of heavy water hanging from the davits or sitting on the foredeck. So I am seeking a virtually ‘transom-less design’, or at minimum a ‘framed-transom’ that would allow for very quick water egress.

    I also find most of the smaller RIBs to be very confining and tight on the interior space as a result of the full diameter tubes utilized in their design. The actual width of the boats between the innermost tube sides is very confining with respect to allowing for two full size adults to sit across from one another, let alone a steering console, cooler etc. Then if you add in all of the ‘stylized’ seats for passengers, center console for driver, engine mountings and drains, etc,etc, you end up with very little interior volume to carry people, dive equip, etc, and all of those other items (food, supplies, bikes, etc) being transported to and from the shore. Remember, in the islands your tender becomes your car!!

    One solution to increasing the onboard space of any RIB is to make use of only ‘half-round’ or ‘D-shaped’ buoyancy tubes at the beam extremities of the craft. This idea is at the core of the ‘SAFE’ system (I’ve attached a reference drawing). These ‘tubes’ might be constructed of either an inflatable material as normal for the current industry, or simply be a foam collar that might be glued on, or a combination of both.

    Another solution to increasing the onboard space of the smaller RIBs is to make them wider…exaggerated wide. One manufacturer currently refers to this as his “wide body” models. The problem here is the deadrise angles at the bottom surface of the hulls become pretty small, or as it might be termed more ‘flat-bottomed’ rather than V’d. This results in a vessel that slaps or pounds more on the water surface, particularly a choppy one. And this flat bottom loses it directional preferences (control).

    My design reconfigures the bottom of the RIB into a sort of tri-hull arrangement. This totally changes the shallow deadrise equation of the main hull, and provides two ‘channels’ that allow for a sort of air suspension within them. The outer rib keels, or what might be termed sponsons of the tri-hull configuration, act to contain the channels themselves, provide additional buoyancy at the extreme beams of the vessel, and provide a turning edge much like the tunnel sides of the older tunnel-hulled craft. These outer sponsons do not extend forward to the bow area of the craft, which might be confused with being similar to the old ‘cathedral hull’ that was so poor about pounding in choppy waters. It’s totally different. It’s referred to as a stabilized monohull, a slender monohull shape stabilized by two outer sponsons. The more ‘convoluted bottom shape’ of the design will lend ‘form strength’ to the bottom surface, as well as longitudinal rigidity to the whole vessel, allowing for a lighter fiberglass lay-up to achieve proper strength than is the case with the large flat-panel areas of the traditional V-bottomed hull.
     
  9. michael pierzga
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    michael pierzga Senior Member

    Nothing wrong with a wide rib concept as a space storage issue. Perhaps its even the best way to go. Very many people use the cat rib infalatbles and love them. . They would be difficult to unground or handle on the rocky beach. With a Vee bottom tender you take the removable thwart seat from the tender, put it on the beach and pull the tenders VEE over the plywood thwart like a marine railway..hard to do with two vee's.

    Tubes are very effective low speed spray rails. Small tube , more spray.

    Jet propulsion is a disaster.

    Every jet tender Ive ever know was either riuned by flooding, unfixable because spares were not available, out of fuel , dead battery or the tunnel bucket arangment was damaged do to grounding. Pick a plastic bag up in the harbour at night with your jet and you are going for a swim. On a outboard tenders if the prop fouls, tilt and clean..if the motor blows..buy a new one.

    Additionally, A tender MUST be self bailing and MUST have a completely unobstructed cockpit sole. floor space...no engine room hood, no center console, seats, no batteries, bilge pump,no fixed fuel tank, no junk. I must fequently JUMP, flying leap, into a tender. I frequenlty handle 100 meter of rope, anchors, 8 jerry jugs of fuel, sails..you name it. The object of a tender is seaworthy utility and maximiun payload.
     
  10. CatBuilder

    CatBuilder Previous Member

    Now I can't agree with all of this. Depending on your requirements, tenders serve vastly different purposes.

    I ran this tender while taking my owners and their family diving from the megayacht I used to run. It broke many of your rules, but it was perfect for taking 4 people out for a dive or ashore:

    http://www.novurania.com/

    You are talking only about your *personal* requirements for a tender here. You are neglecting that many people have different requirements than jumping with a flying leap into a tender. Many of us board them at our vessels at anchor or at a dock while transporting passengers.

    In my personal case, on my charter boats, I provide a safe, dry, comfortable ride to guests with luggage. I need a large tender with a console or seating to transport these people. Your feet are never wet because there is a true bilge and the bilge pump takes care of any rainwater.

    You are talking only about the needs of a solo cruiser and/or his wife who may not be divers. Many people have a different and expanded set of requirements for their tender, just like many people have different requirements in their main vessel.

    One thing I will certainly have in my next large tender to keep weight down and maximize available space is the "Euro Helm." Not sure what that's called in Europe. :)

    [​IMG]
     
  11. michael pierzga
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    michael pierzga Senior Member

    These are toys. Nice wind in your face toys...not seaman like yacht tenders. Tenders must be work barges..Im mountain climbing and laying 50kg anchor with tenders. Those toys pictured could never perform the primary tender role on a passagemeker
     

    Attached Files:

  12. CatBuilder

    CatBuilder Previous Member

    Yes, as I was saying.. you are telling us your personal needs for a tender.

    That would be the same as me telling you should use a catamaran in your pictures because your boat heels too much and will roll at anchor, causing you to have an uncomfortable ride and loose sleep. Your idea of what is important in a boat will not always be the same as the next guy.

    Different people require different things from boats. Your requirements list is not the same as mine. I transport passengers and luggage from docks to yachts as well as water and fuel at times. I use the tender to take people diving and waterskiing. I use the tender to take people to the beach. I don't carry 50kg boulders in it or use inefficient anchors that only work in rocks. I have a clean, "yachtsman" image to uphold to attract customers.

    There is not a single answer. Boats are always compromises and different people use a tender in different ways.

    BTW: Where is the tender in your pictures? I see only the mother ship.
     
  13. michael pierzga
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    michael pierzga Senior Member

    Back to the original topic of the thread. Since most people reading this are custom building their vessel it would be wise to ,while in the construction phase, conceive both Bow and stern storage. Stern storage is seamanlike, but very clumsy and in your face when maneuvering in harbours. Many times when stern too its becomes impossible to launch without moving off. The tender is your shopping taxi and tugboat in harbour and you must be able to deploy. Bow storage for coastal hoping and harbour work is a very nice ability to have available. .
     
  14. michael pierzga
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    michael pierzga Senior Member

    Remember catbuilder..you never know what the future use of the yacht will be. When building it would be a mistake not to concieve of an all weather work tender type solution to tender storage. Toys are toys..a tender is a function of the vessel.
     

  15. CatBuilder

    CatBuilder Previous Member

    Actually, Michael, I agree 100% with your last two posts. :)

    The tender issue is a very challenging one, but at least it is easy to accommodate the type of work tender you are talking about. It weighs very little and will be easier to manage than that toys I need in my line of work.

    FWIW: I agree with you in principle, as a cruiser, but I am seeking to find a good way to keep a large tender on a catamaran for work purposes, which involve everything I have already mentioned.

    Also, while looking up pictures for the "euro helm", I found a very bad tender location. Look at this one! :eek:

    [​IMG]
     
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