50 knots from a Levi Triana 25 Help!

[cakecakeboy]

Hi All

I'm new to this forum, so hi to everyone!

I need a bit of help, I have decided I want to build a fast, competative classic boat and probably start with the Levi designed Triana 25 (although I am not atached to one just yet!)

The issue I have is is it actually possible to get 50 knots out of one of these hulls without ridiculous HP. I have only been on this track for a while but have already discovered the big differences between surface drives and legs etc and heavy diesels compared to petrol, but in the UK diesel is still the cheaper option and I want efficiency as well.....

Any pointers gratfully received...

Thanks

Mike

[daiquiri]

Triana 25 is very akin to Speranzella, a very famous competition boat by Sonny Levi, because it derives from Speranzella design.
Triana 25 attains around 35 kts, while Speranzella was able to reach around 46 knots with 2x400 HP engines. So you will probably need a similar power to attain your target speed. Basically, it would mean approximately doubling the power for which Triana was designed (2x 170-220 HP, though some models arrived to 320 HP), therefore it goes without saying that important structural modifications and weight reduction would be necessary in order to adapt the hull for such high speeds. It would be much safer and simpler, imho, if you could find blueprints for Speranzella and start from that design.
Cheers

[anthony goodson]

"But in the UK diesel is still the cheaper option" How so?

[cakecakeboy]

Unless I am mistaken, and I may well be I believe that using diesel is the cheaper option? I guess diesel is more efficient and is it not true that there is some form of allowance on tax on diesel????

To be honest it is not my bag yet and i am trying to understand the direction needed to make a boat hit 50 knots efficiently and cost effectively as possible!

Cheers

[anthony goodson]

Tax allowances on red are limited now to commercial usage and the heating and other domestic usage on pleasure craft .Using lower tax red for pleasure craft propulsion will leave you liable to losing your vessel your fortune and possibly your freedom, The initial outlay for a diesel powerplant will need many engine hours to recoup, so do your sums carefully, good luck.

[cakecakeboy]

Originally Posted by anthony goodson

Tax allowances on red are limited now to commercial usage and the heating and other domestic usage on pleasure craft .Using lower tax red for pleasure craft propulsion will leave you liable to losing your vessel your fortune and possibly your freedom, The initial outlay for a diesel powerplant will need many engine hours to recoup, so do your sums carefully, good luck.

So, the fact the boat world still installs diesels and look for diesels and secondhand boats with diesels are more expensive is really historic and no longer based on fact? Genuine question, in card diesels are more economic, still a bit more pricey but......

Any more info on the original request please? I have googled Speranzella and found a couple of boats one at 33 ft and one shorter, the shorter one only gives 25 knots the larger looks stunning, but no performance figures, I have both of his (Levi) books on their way to me so will learn more from these as well.....

[anthony goodson]

Yes it is of course true that new or secondhand diesel boats are more expensive. I guess I saw that fact as one of the building blocks for the comment I just made.

[Submarine Tom]

If you want to go 50 knots then you have no business talking about economy my friend.

Safety is another factor not to be overlooked. You need to start with a 50 knot design. You are making a large mistake if you try and make a 35 knot design go 50kts.

"Design" is just another word for "calculated compromise".

I believe this addresses all your questions.

-Tom

[daiquiri]

Originally Posted by cakecakeboy

Any more info on the original request please?

Sonny Levi has used a following formula for determining the power necessary for his hulls:

V = K x (LWL^0.25 ) x ( SHP / D )^0.5

Where:
V = maximum velocity in kts
LWL and SHP are, well...
D is diplacement in tonnes.

K is a coefficient, which varied in function of propulsor type:

• 2 I/B engines with a conventional shaft: K = 1.5
• 2 O/B or 2 sterndrives = from 1.5 to 1.6
• 2 surface drives = 1.8

You can use it to calculate by yourself how does it translate to your boat, based on what you know (LWL, weight, propulsion type).

[sean-nós]

I have one for you cakecakeboy I am building a 1954 crackerbox with a 5.7 v8 see what you think.
http://s753.photobucket.com/albums/x...er/crackerbox/

[daiquiri]

Sean-nos, thanks!!!
That's the boat I was trying to find in the last couple of weeks. I saw a pic once, but didn't know the name. Now I do - Cracker Box. Thanks to you I've found it at the Glen-l site: http://www.glen-l.com/designs/inboard/crackerbox.html
This one in particular: http://www.glen-l.com/designs/inboard/dsn-cbxd.html is one of the most handsome little classic toys for big boys I've seen around.

P.S.
Can be seen in BD.net gallery too:
http://www.boatdesign.net/gallery/sh...o/5317/cat/500
http://www.boatdesign.net/gallery/sh...php/photo/5316

[anthony goodson]

Sean-nos
You seem to produce some remarkable results under what most of us would regard as difficult circumstances, well done ,and thankyou for sharing them.

[sean-nós]

Yep thats the one that made up my mind.My build is on wooden boat building and resto under new boatbuilder. I am a member of a club in the UK "CMBA" the lads there are a great source of info and parts for old boats they meet up a lot my last boat was brought over to Cardiff this year for the show.

[sean-nós]

Originally Posted by anthony goodson

Sean-nos
You seem to produce some remarkable results under what most of us would regard as difficult circumstances, well done ,and thankyou for sharing them.

I am tight for space alright

[cakecakeboy]

Originally Posted by daiquiri

Sonny Levi has used a following formula for determining the power necessary for his hulls:

V = K x (LWL^0.25 ) x ( SHP / D )^0.5

Where:
V = maximum velocity in kts
LWL and SHP are, well...
D is diplacement in tonnes.

K is a coefficient, which varied in function of propulsor type:

• 2 I/B engines with a conventional shaft: K = 1.5
• 2 O/B or 2 sterndrives = from 1.5 to 1.6
• 2 surface drives = 1.8

You can use it to calculate by yourself how does it translate to your boat, based on what you know (LWL, weight, propulsion type).

Great and thanks for the info, I will be able to play with this and as I think I said I have both of his books on the way to me at the moment and want to understand the engineering more fully..... Lots to learn I believe