sib top speed needed for insurance

keith81 · 20 May 2013, 16:28

Trying to get a qoute and they have asked me for the above sib is a 3.8m seasearch with alloy floor weighing about 90 kg and motor is a new mariner 20 hp fourstroke weighing 50kg
Thanks for any help

whisper · 20 May 2013, 16:39

Ring craft insure for a quote, I don't think they ask that.

Think around 22 knots? may be just over. PeterM might know

Nos4r2 · 20 May 2013, 16:40

THey really are a pain in the neck aren't they.

How are you supposed to know-there's no data available. If there was, they'd already have it.

I'd estimate at an absolute max of 25 knots, but thats all it is-an estimate.

PeterM · 20 May 2013, 16:42

Sounds about right 22-25 ish ...but that will fell like about 100mph in most SIBS..( Im excluding zapcat/ thunder cat types in this)

paddlers · 20 May 2013, 17:05

I wonder when the slippery buggers will start asking if it's got a kill cord ??

Nick Hearne · 20 May 2013, 20:21

I would say 18 to 20 knots max!

whisper · 20 May 2013, 20:46

Quote:

Originally Posted by Nick Hearne

I would say 18 to 20 knots max!

Is that with a pallet of bricks

Nick Hearne · 20 May 2013, 20:50

Quote:

Originally Posted by whisper

Is that with a pallet of bricks

No just comparing it to a 3.8 quicksilver & Tohatsu sibs both with 25hp 2st on them!

whisper · 20 May 2013, 21:15

Quote:

Originally Posted by Nick Hearne

No just comparing it to a 3.8 quicksilver & Tohatsu sibs both with 25hp 2st on them!

Go for 18-20 then, might mean a cheaper quote

keith81 · 20 May 2013, 21:52

Thanks for the help guys first quote came back at £215 got in touch craft insure they quoted me £70 no brainer I reckon. thanks again.

whisper · 20 May 2013, 21:52

Quote:

Originally Posted by keith81

Thanks for the help guys first quote came back at £215 got in touch craft insure they quoted me £70 no brainer I reckon. thanks again.

Well done you

Poly · 21 May 2013, 19:24

Quote:

Originally Posted by Nos4r2

How are you supposed to know-there's no data available. If there was, they'd already have it.

you can work out the maximum speed the engine is capable of though:

Max speed = max_rpm x 60 x prop_pitch (inches) / gearbox_ratio x 72913

You will never go faster than that with that engine / prop combo. (And probably only 90% of it).

Quote:

Originally Posted by whisper

Go for 18-20 then, might mean a cheaper quote

Never a good idea to mislead insurers on 'potential risk' though - it gives them an excuse later.

mister p · 21 May 2013, 21:41

Quote:

Originally Posted by Poly

you can work out the maximum speed the engine is capable of though:

Max speed = max_rpm x 60 x prop_pitch (inches) / gearbox_ratio x 72913

You will never go faster than that with that engine / prop combo. (And probably only 90% of it).

Never a good idea to mislead insurers on 'potential risk' though - it gives them an excuse later.

There has to be a "mass" there somewhere?

Poly · 21 May 2013, 21:54

Quote:

Originally Posted by mister p

There has to be a "mass" there somewhere?

No. This is nothing to do with power or acceleration - this is simply how fast a particular prop spinning through water (with zero slip) could propel a boat. The boat could be the QE2 or a carbon fibre canoe - but it will never be able to go faster than the engine can move the prop.

Alanpatt · 01 June 2013, 18:08

Whaaaaa? You lost me at max rpm.... :o)