Mad Marine

[Andy HustlerParticipant @andyhustler32076]

My mad marine friend is at it again !!!! he has changed his ,mind now anbout the sub and want to build a 6' powerboat , powerd by a petrol engine from a strimmer . Personaly i think he is as fruity as a nut case or is ti the other way around .His basic design is a wooden hull but god knows what size prop or rudder he would need .So as always it's down to me to do the leg work even though this Nutty ex marine wouild not find any problem taking on the taliban he's not to good on the pc .So any advice on building a " beast " would be great

Many thanks

Andy from Cardiff

[Andy HustlerParticipant @andyhustler32076]

[Paul TParticipant @pault84577]

Andy

I would be happy and proud to help your marine friend.

The problem wont be the prop or rudder as they are fairly to specify (depending upon the hull). By far the biggest worry would be keeping the strimmer engine cool.

If your marine friend is set on building this beast he should be looking for a Blata (or similar) water cooled engine.

Meanwhile does he have any idea about the boats design and has he ever built a large model before?

Paul

[Andy HustlerParticipant @andyhustler32076]

Just spoke to my mad friend and has has found a programme on line that you feed the details in to and it gives you a design . I think the only thing he has built before is an airfix model so not alot of help there !!!!!! I did tell him about water cooling the motor but wasnt quite sure myself as i have not dealt with this before only small motors but i would imagine it's wraping a metal tube around the motor with an inlet under the hull and an outlet on the side i guess ????? The motor is about 70cc petrol . I honestly dread to see it goe , it will go off like a scalded cat on acid on only in an old dock or a flat calm sea as i cannot see many lakes , big enough , that would let him use it !!!

Many thanks

Andy

[Paul TParticipant @pault84577]

Andy

Air cooled engines such as those in strimmers use a built in fan to force cool air around the cylinder head. It is not such a simple matter to cool just by adding a coil.

When installed in an enclosed hull the engine will very soon overheat and so your friend will have to force air around the engine with electric fans and ensure a large volume hot air exhaust is vented away from the engine and out of the hull.

70cc might prove to be to big for a 6ft hull without a large amount of extra strengtheners being added to the frame, for 70cc I would recommend a minimum hull length of 8ft and a design based upon a Huntsman 31 or Perkasa style of boat.

Paul

[ashley needhamParticipant @ashleyneedham69188]

Hmm… sounds like too much trouble to me, there is considerable difficulty in moving that much air about, and not distorting the hull with the heat.

A 6 foot sub would be more of a goer.. v impressive on the pond even if it didnt submerge.

OR a 6 foot sharks back, with one large fin…now that WOULD be the business.

Ashley Hmmmm ideas ideas

[ashley needhamParticipant @ashleyneedham69188]

I am suddenly overcome by the desire to build something along those lines…just need the tail to wag a bit. Perhaps 4 feet long though.or i could make a new top for my sub?

Ashley

[Paul TParticipant @pault84577]

Ashley

You could use the forward motion of the shark to impart movement into the tail and a heavy duty servo to open the jaws

Paul

[ashley needhamParticipant @ashleyneedham69188]

Paul. Ah ha. Dont say you have not given this the odd thought now and then!

The trouble with this sort of thing is, it works as a bit of fun for a while and then becomes a bit tired..

I rather fancy making a sharks fin top for my sub, as big as it will handle. That would look good, and i can change it at the pond side for the usual top for conventional boating. I can imagine the looks at the pond side, as you stand away from the edge to hide the transmitter, and cruise the fin around the middle of the lake. I have Blue Styrofoam to use, weighs nothing and I should be able to make a decent size fin without affecting stability.

Oh yes. The next project..(after the CURRENT project..) quick, easy and very effective.. just my style.

Ashley

[Andy HustlerParticipant @andyhustler32076]

I would like to thank ashley for his patience in sorting out and sending me the blue prints for Nelson/Rodney after a long struggle i haved managed to get the plans at long last .Ashley many thanks for your time and patience

Andy

[ashley needhamParticipant @ashleyneedham69188]

Andy. No probs. Our home mails must have been blocked for some reason, you have obviously recieved the PDF from my work address.

Clip your mate around the ear and instruct him to do the sub, and stop toying with quite frankly a very difficult and possibly quite dangerous idea (strimmer power).

IF he is wanting large i/c then it would be best to purchase a proper large offshore hull, and fit as per the recommended route regarding engines.

A novice wooden hull and a strimmer engine sounds like a recepie for hospital, to me…

A builders yard will provide sufficient inspiration for a sub. Pipes of all sizes, and fittings…end caps and whatnot.

ABS tube and hemispheres, glue and ….STUFF.. is available from EMA Model supplies. Nice big shiny 6 bladed crescent prop on the back. Luvly.

Ashley

[LARRY WHETTONParticipant @larrywhetton68737]

How about a sea queen a big 4ft hull length …………..built for air cooled motors and a easy build LARRY.

[ashley needhamParticipant @ashleyneedham69188]

Larry, very nice, but still not man enougfh for a 70cc strimmer motor i recon.

Funny, the Fantome was sold to be powered by a "fox" 26cc engine, when first sold.

Ashley

[Andy HustlerParticipant @andyhustler32076]

I would like to thak ashley very much for his time and patience in sending me the plans for Rodney/Nelson . Ashley has taken alot of time in finding these plans and sending them to me , several times !!!!, and eventualy we got it right so it's off to the ciopy shop on tuesday to get some drawings enlarged i was thinking of 4 times the size which should give me about 4 foot of boat , yes a big boat but it leaves me room to get my spade like hands inside .

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