Massively overpowered dinghies, again

[[2068]]

7hp each side on a 2.40m tender - that's not too bad, is it?

 

[hlb]

Suzumar. I had one of them, it started falling to bit's after 12 months.

Dont worry about over powering it, it wont last that long anyway.

 

[[2068]]

It's a Quicksilver, 2005.
One new seat, two sets of floorboards.

 

[Beyondhelp]

amazing stability given those two 7 marine outboards where are the fuel tanks?!!

 

[Ripster]

amazing stability given those two 7 marine outboards where are the fuel tanks?!!

Thats obvious, fuel will be kept in the bow chamber with the weight acting as ballast and countering the wt of the engines. If you do this, you just have to be a little more careful not to bump into anything sharp

 

[Beyondhelp]

Ahh yes of course... Its so obvious now!

 

[MapisM]

i am posting this here with all the fun-loving speed-crazy petrolhead boaties. That's you, that is.

Well, thanks for thinking about us, in the first place!

Now, let's see if I understood what you're saying: you've got a baby dink with 6.25 times (25/4) its rated power, and a bigger 12' rib rated for 40hp which is now useless, since its 25hp o/b was stolen by the new kid on the block. And which was useless anyway, 'cause awfully underpowered.

So, the real problem is, what are you now going to fit on the 12' dinghy? Here's my 2c.
Just apply the same 6.25 factor to the 40hp rating, and you've found the magic number - exactly 250hp.
Now, it's a smallish RIB after all, so we don't want it to sink due to the o/b weight, do we?
That's why you should look for a Merc 2.5 V6: with its light weight, 2 stroke and almost 9k RPM, it's just the ticket for proper speed.
Not to mention that you could get rid of the stereo, which couldn't keep up with its fantastic sound, anyway.

No worries about insurance, either. Just remove the dot from the "2.5" label and pretend it's a 25hp engine.
By today standards of 4 stroke fat outboards, that's almost believable. Unless you hammer the throttle, that is...

 

[oceanfroggie]

Baaa humbug! 3.5m rib with 30hp has proved safe. Just because a car has an accelerator pedal doesn't mean one has to staple it to the floor all the time.

Put four people on board and that's when the power makes a difference. Weight rather than safety is a bigger factor for tenders on lifts or davits.

We avoid shanty marina caravan parks like the plague when cruising instead anchoring or mooring buoys so reliable tender is important to get ashore.

 

[jfm]

Here are pics from tcm of the flaming hoon machine yesterday in Las Palmas. Looks perfectly warrantable to me, and a bargain at €135. Matt, do you have a vid of it underway? No worries if it's a bit shakey
Also, if anyone has a 36P prop for a yamaha 25 enduro please sent it to matt in Las Palmas

 

[benjenbav]

Here are pics from tcm of the flaming hoon machine yesterday in Las Palmas. Looks perfectly warrantable to me, and a bargain at €135. Matt, do you have a vid of it underway? No worries if it's a bit shakey
Also, if anyone has a 36P prop for a yamaha 25 enduro please sent it to matt in Las Palmas

Excellent stuff. I think Matt needs a bit of cord to fix the paddles in place: maybe just a hair or two further astern - but proper testing is needed to confirm the best location - and voila: trim tabs.

 

[z1ppy]

that looks a whole lot of fun!! good effort!!

Now, time for me to think about re engining Aviator!!

 

[Firefly625]

that looks a whole lot of fun!! good effort!!

Now, time for me to think about re engining Aviator!!

got just the thing..

 

[DTIM]

Thanks for obtaining the photos JFM, looks like a whole lot of fun!

 

[vas]

Right, only thing missing from this thread is a few photos of. Marinised ferrari v12 from the 70ies.
anyone?

 

[Hurricane]

i am posting this here with all the fun-loving speed-crazy petrolhead boaties. That's you, that is.

Here in las palmas I bought a 2.1m runabout dink secondhand for 135euros, Suzumar with inflatable keel and single lump of plywood floor and set about looking for a suitable motor. The other dink I have is 3.6metres (12feet) and has modest 25hp on it altho it can take (it says) 40hp - the idea is that the baby dink allows other people to go elsewhere without waiting around cos we only had the one dink, and/or we can take the small dink for easier hoiking it up the beach. Altho it's not too hard dragging the heavy one up the beach - if you sort of drag at the dinghy pathetically whilst beached.....pretty soon some other people always come to help. But anyway, i need a motor for the new baby dink. Hm.

Many hereabout are well-known practitioners of spectacularly overpowering the dinghy. Frinstance i saw that JFM had something like 40hp on the back of a 9-10ft dinghy a while back, very good value, and from a distance his dink was completely lost from view in all the airborne spume and wash. Superb stuff.

Soo, i put the 25hp motor on the 2.1 metre dinghy (max rated 4hp) to see wottle it do. Yeehah! It does 9knots at just over tickover and erm, i saw 24knots on the hh gps at half-throttle but the sea conditions outside las palmas marina here aren't ideal for full-on Coniston-type speed tests. Main thing is the fabulous acceleration, wham, straight up to 20knots in seconds. Also excelent cornering - still bags of power to turn at speed instread of all that slower stuff on corners as the prop sort of loses it if not loads of spare power. I spose it's a bit of a waste cos i can't really see us ever using maximum power, really. But 10hp would be fine, easily.

No sign yet of the transom falling off or any such nonsense. The only thing stopping me from putting gianty motor on it is that the whole idea was a lighter setup. Also, erm, actually carrying out the initial speed tests as above have somewhat reduced crew appetite for a massive motor on that dink, so i think a secondhand 5hp 2-stroke will be just fine. Well, okay, maybe 6. Or 8....

As the engine gets bigger, you may need to add some fins - to keep the bow from flipping over the stern - a sort of inverted pitch pole!!!

see here

 

[ccscott49]

The 30 yam 2t, on our zodiac 3.4m yachtline rib is a bit underpowered in my opinion, I've seen a 50 yam 2t, going for a song, it may end up on the back!!

 

[MapisM]

Right, only thing missing from this thread is a few photos of. Marinised ferrari v12 from the 70ies.
anyone?

If you actually meant the 12 boxer, you can have a look at that in this video.

 

[MapisM]

got just the thing..

Now, that's a real masterpiece.
If and when I'll consider another toy, that's what I'd love to have in its business end.

 

[MapisM]

As the engine gets bigger, you may need to add some fins - to keep the bow from flipping over the stern

Did you actually try it without the fins, fully trimmed in upon start?
As a rule of thumb, fins should be more necessary with underpowered rigs, rather than the other way round...

 

[jfm]

Did you actually try it without the fins, fully trimmed in upon start?
As a rule of thumb, fins should be more necessary with underpowered rigs, rather than the other way round...

I had the same boat MapisM, except i had the newer efi version of Yam40 - pic above on page 1 of this thread. I completely agree what you say above, but this boat was weird. Even with the engine trim fully in, the bow would lift way too much as you gun the throttle. It was ok with someone sitting in the bow, but not with 1 passenger. I've no idea why; it must have a funny hull shape or something. IIRC the firm that supplied hurricane's took it for a sea trial and had they same problem, so they fitted those doel fins before handing the boat over to hurric.

I hate those doel fin things so I had a mahogany wedge made to sandwich onto the back of the transom, to get more trim in angle, but I sold the boat suddenly when I broke my leg in 2010 so I never got around to fitting the wedge.

Anyway, in three sentences, can you give me the spec of the beautiful Ilmor engine/surface drive masterpiece in the picture above?