Tenders stored on foredeck

[michael pierzga]

The" under over " solution that you picture is one of the most attractive ,functional storage solutions that I know of. under for harbour work....nightime haulout and day sailing, over and on deck for at sea work. Many of the very finest yacht use this line of thought.

 

[sabahcat]

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

Pretty sure it is Brian
There are a few versions of it getting around in australia
Have seen sizable boats built from it so I imagine for my 3.8 m tender it'll be fine

 

[brian eiland]

Some Rough Sketches

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.
Any RIB on a rocky beach is going to experience excessive wear. Personally I try to avoid them if at all possible. You might notice I've suggested a 'replacable' portion to the outer sponsons of my rib idea, for both construction ease as well as built of a optional material that might suffer less damage in certain situations (more compliant).

Tubes are very effective low speed spray rails. Small tube , more spray.
My tubes are not smaller in dia, but actually larger...they are just half tubes. If you saw the whole idea you would realize how much 'overhang' the front portion of the RIB has over its hull shape at that point.

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.

I suspect you have experienced primarily rental jet skis, etc. These applications subject the motors to a lot more wetness, plus most suffer from poor maintence. This application could surround the motor in an inner open top box to protect it from lots of this wetness...and other thoughts. Jet propulsion has a lot of positives working for it including safety to divers and children playing with them. Plus theif deterence compared to outboard engines. Of course my RIB can still make use of an outboard.

Out of fuel, dead battery...these are comman symptoms to all.

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.

I appreciate what you are getting at here, but in a mid size tender a center console and and some seating are features most of the boat owners are seeking. Leave them off...lose customers.

These are a few sketches of that RIB I proposed in #138 above

 

[Alik]

I appreciate what you are getting at here, but in a mid size tender a center console and and some seating are features most of the boat owners are seeking. Leave them off...lose customers.

These are a few sketches of that RIB I proposed in #138 above

I tested small boat with such tri-hull recently; initial stability is very low that is a problem in case of tender. Underway on oblique waves, the boat was directionally unstable.

 

[brian eiland]

http://www.novurania.com/

On this vessel I see that the bow rails eliminate a lot of potential seating area, and that stern seat eliminates a lot also. The center console is too big The stern area is wasited. With D-type tube concept this vessel would offer a lot more usable space.

If storage on the bow is comtemplated then you want a tender that will IMMMEADIATELY empty itself of all water that it might collect from a big wave, a bow burying event, etc. This vessel would act like a big tub with a slow drain. It needs an open transom of some sort.

 

[Alik]

Yes, D-tube is good idea for cockpit space and we have 3 designs launched with this concept, BUT the boat is heavier.

 

[brian eiland]

Tri-Hull references

Lots of tri-hull discussions, and illustrations:
http://www.boatdesign.net/forums/boat-design/trimaran-motorboat-stabilized-monohull-29665.html

 

[Alik]

Lots of tri-hull discussions, and illustrations:
http://www.boatdesign.net/forums/boat-design/trimaran-motorboat-stabilized-monohull-29665.html

Thanks, but those not for planing craft.

 

[CatBuilder]

On this vessel I see that the bow rails eliminate a lot of potential seating area, and that stern seat eliminates a lot also. The center console is too big The stern area is wasited. With D-type tube concept this vessel would offer a lot more usable space.

If storage on the bow is comtemplated then you want a tender that will IMMMEADIATELY empty itself of all water that it might collect from a big wave, a bow burying event, etc. This vessel would act like a big tub with a slow drain. It needs an open transom of some sort.

A couple comments:

First, you couldn't sit on the tubes where the bow rails are. Your feet wouldn't touch the sole and you'd flip out too easily. I agree the stern area is wasted and could have been used more. However, it houses fuel and batteries, IIRC. Bilge pump, too, I think. It was a few years back, so I'm not recalling.

This boat didn't go to sea. It was a *tender*. We used it in protected water to go diving and to go ashore when at anchor. None of the safety issues you are bringing up were relevant to the use of this boat as a tender to a megayacht.

This gets back to my initial post. We all have different uses for tenders. You are assuming there could be a "bow burying event", but in reality, I could plane all the time because it was so calm, or was idling through no wake areas in harbors with it.

If I had to go to sea, I sometimes used the other tender, although the RIB gave a much better ride in rough conditions:

Either way, these were *tenders* (to a large boat) and were not used to battle poor conditions. I had a 33M (110ft) vessel with active stabilizers to take care of rough conditions at sea. In the case of going to sea in the large vessel, both of these boats were up on our aft deck (top level). These were used for fun, for leisure and for transportation in harbors... the same way 99% of all tenders are used.

BTW: I like your tri-hull tender! Very nice.

 

[michael pierzga]

Gee Brian as I said...many different solutions to a tender. Some people need toys so obviously a high speed, wind in your face, lets do a tour, tender is the way to go. For everyday, primary tender, toys wont work .

Your multi hull tender has merit... many people love the load carrying ability and space. Wide tenders are much easier for Old folks to board and find a seat in. I actually have a boarding ladder built into my tender for old folks access. By all means explore the design possibility. Make it 3.5 meters and I might buy one tomorrow. The Nautica Cat is very popular on the superyachts. http://www.nauticaintl.com/Boats/Catamaran/catamaran17.htm

Get rid of the sharp egdes on your design .. this weekend Im repairing the sharp underwater edges of my tender , with epoxy and Biax tape. Make them soft and able to absorb bumps. I " bump" the tender every time I store it. I also "beach" a tender, because the guests , want to go to THAT restaurant on the beach, the small port has no available tender loading , unloading space, 50 times a season.
And jet...forget it. I have zero experience with jets ski. The yachts around me use castoldi diesel jet tenders. Expensive first class gear, And they curse them because of flooding damage and lack of spare parts, particularly jet bucket pieces, on the road. Realize that many times I am operating my tender in extreme shallow water...outboard tilted up, prop nearly spinning in the air, in order to access places of intrest on the inside of an esturary. A jet would die..clogged with weed and junk.

http://www.castoldijet.it/jettenders/model14.php

 

[brian eiland]

...This boat didn't go to sea. It was a *tender*. We used it in protected water to go diving and to go ashore when at anchor. None of the safety issues you are bringing up were relevant to the use of this boat as a tender to a megayacht.

Maybe a slight misunderstanding here. I wasn't talking about the tender going to sea on its own...rather I was talking about putting a tender on the front tramp area of my gamefishing cat (keep it out of fishing area), and my concerns that it could fill with water and become a problem in storm conditions. I wanted that tender to be fully drainable in seconds.

 

[brian eiland]

.. The Nautica Cat is very popular on the superyachts. http://www.nauticaintl.com/Boats/Catamaran/catamaran17.htm

That is a very nice tender, but it could have much more 'usable space' with D-tubes, and better treatment of that aft area that is essentially corrided off. Either make an aft seating area covering that stuff in the stern, and/or push some of it up under the console.

Get rid of the sharp egdes on your design .. this weekend Im repairing the sharp underwater edges of my tender , with epoxy and Biax tape. Make them soft and able to absorb bumps. I " bump" the tender every time I store it. I also "beach" a tender, because the guests , want to go to THAT restaurant on the beach, the small port has no available tender loading , unloading space, 50 times a season.

I totally agree, too sharp an edge on the underwater sponsons. But I had though they might be fashioned of tough rubber bumper material such as THIS, or THIS

 

[michael pierzga]

And Brian..your " D" section is very worthwhile. The major cause of tube failure on every Rib Ive ever owned is the interface between tube and the rigid bottom..On the inside of the rib. This deck to tube joint become full of sand and stones and chafes thru the tubing, destroying the tube. Very complex to patch this area. For the past few years I have, to prolong the life of the tube by preventing debris from accumulating, caulked the deck to tube interface, skin to hull , with cheap silicon seal...seems to work. Better to eliminate this joint.

 

[sabahcat]

With D-type tube concept this vessel would offer a lot more usable space.

On a small scale, but built using Polycore/nidacore/naidaplast/hexacore (whatever they want to call it this week)

http://www.multihullhaven.com.au/Mk_2_elevator_Miss_B_Haven.jpg

Interesting wheel design
Free replacements found on almost any beach in these parts

 

[brian eiland]

Nice and clean and simple
....but it needs some really big drains for my liking

...and its got those ramp/beach rollers Michael was requesting

I had thought something like this could be rotomolded from polyethylene or similar