New member presentation / Roca Speed Rails wanted

[El Español]

Hello from España, ole!

I’m reading you guys from many years ago, at offshoreonly and screamamfly and now formally join the speed communities!

We are a bunch of friends located in Palma de Mallorca and Marbella (Spain) with some nice boats and GAS in veins.

Today I want to show you an special boat I was restoring. It’s a beautiful 25ft Tullio Abbate, an Italian well recognised manufacturer.



The model was originally designed for I/O, but they built some units with kevlar hull (I guess not the best kevlar 49 McMannus) for single outboard racing. And as I know probably the unique with twins.



This boat was built by Offshore Agency Prettin in collab with Abbate. It has an oversized tubular bracket with strong torsion bars along the hull and an a 3” wood core stern.



Non cracks or stress signals after the years. It’s true that the boat was only in the hands of OA Prettin and very well cared.

***

Let’s deep in materia!

- The boat is 1.300 pounds + 250 in inox. Steel + 850 engines (Twin Merc V6 200HP 2T Carb 200hrs);

- Has 23” Attwood Ballistic Couped & Labed Props with over ventilation (0.6” holes).

- Considering my Props as 24” because of couped design + 1.87:1 gear relation, my numbers are:

45 MPH at 4.000RPM, 7% Slip (cruiser speed)
50 MPH at 4.400RPM, 7% Slip
55 MPH at 4.800RPM, 6.5% Slip

you can run 45MPH, just at half gas and 55MPH with no more tan 2/3 gas.

It runs amazing, nice attitude, very low consumption, but!!!! At 55MPH it develops terrible CHINE WALKING!!!







My max. Speed “driving through” was 62MPH. If you push the hummers it revs immediately fast. It seems will not has any problem to touch 5.700RPM with 0º Trim and current lower engines. I guess, when they will on point could reach 5.900RPM

***

I was reading all post about in this amazing forum and got very deep researching before come here to ask, because I appreciate a lot your knowledge.

The main problem is a longitudinal sustainability lack

ISSUES:

1º the bracket: I know it’s almost double sized of you recommend + the transom has also a severe angle. I guess the props it can be 60” away from the bottom.



But I can’t cut it, it’s an identity of this
boat. Thus, my plan is to improve as much as I can with this thing.

2º the engines height: The boat will be out of the water in one month, then I will measure them properly. I guess the cav plate is 0 or 1” bellow the bottom.



I learn from you guys and from Gill standards that around 60MPH the water after the bottom exits at 4% inclination. This is translated to the rule of going up 1/12” for every 1”. Probably I will be 4 or 5” lower than I must.



As I have standard lower units, I will give 1/2” of prudence when I will raise them + install PSI gauges.

when boat will by at my garage, and I will measure it good, I will ask you all and together we will find the proper height.



(Mikel’s explanations)

3º make the steering stronger: I have single hyd + standard tie bar. I have purchased a heavy dutty rear bar. I’m 1/3 Toe in.

4º trim tabs: I will install parallel to the water a pair of lencos with led position indicators + squared “custom” trim tabs. It will be mounted just as a continuation of the strakes, with customized T-fins at the external side of the tab designed my friend Mikel.

they will be mounted just on the limit of the bottom, and will run normally in negative trims. Also will make the bracket smaller (based on Arneson Rockers ideas)

5º The Strakes: they are very classical european style. Very thin, not prominent, and even not parallel to the water. It’s with the height of the engines the biggest issue.

With such low engines I got to much stern lift, then It leads to a longitudinal lack of sustainability.

When I will rise the engines, If I don’t give the boat also a good stand points, it will be loosing again the equilibrium.

For this I have found the best solution. The Ocke Mannerfelt Speed Rails. For those who don’t know them. They are just a simple aluminium slats fixed to the strakes. They make te strakes more prominent and with a concave design, they make more lift using the energy of the lateral displacement of the water.




Roca was a Swedish company which stops making the Mannerfelt Speed Rails 10 years ago.

The “Roca Speed Rails” weren’t very popular in USA. I guess because in USA you use to build boats with wide and strong strakes. Then non extra is needed.




I wish a fellow from our forum still had a set of this old Roca Speed Rails and would be open to sell them. It would be very very helpful!!

Im very happy writing my first post, I will be active!

Javier.

[Chaz]

Hello Javier, Welcome to S+F ..

Looking at you hull, I would think you would get more speed and better handling if you put your efforts towards building a pad on the keel, rather than worrying about making the strakes more exaggerated.
Nothing crazy, just square up that barrel on the bottom ..

[CUDA]

Bingo!

[El Español]

Uff!!!! I was discussing about other day with a friend. Running on a pad is not very common on this side of the pond. But, the Mediterranean sea gives a bunch of “flat like a lake days”, soo it’s possible to do it.

I have also an smaller boat on mind made by simply fibreglass that would be great to build a pad in her an test the concept.

Here we have a bunch of glastrons hulls to try. As you mention, It’s just twist-on the hull, cut the barrel and sharp!

With the Tullio Abbate it would be a big work for me, because it has a reinforced bottom with Kevlar, 3” inches stern,, who will got the hand in the hornet’s nest??? will post pictures,, plus twist-on that “heavy thing”.

Thanks guys, Javier.

[LakeFever]

Welcome aboard Javier, very nice looking rig you have there.

[rock]

Welcome to the site. The pad will do more than you can imagine. Get the boat out of the water so it can run. Boats are faster thru air than water.

Rock

[El Español]

Thank you guys! I must try it 100%. Next will de a 21ft single V6, powerplate, nosecone and a nice PAD!

[CUDA]

24 Bat boat

Pad view

[scott reierson]

I saw Tullio Abbate boats on display at the Miami Boat show long ago. Probably still have the brochures.

I've seen those speed rail extrusions before. We had something similar to that idea marketed around here 40+ years ago. If I remember correctly I think it had a connection with Volvo Marine service centers and or dealers. I looked at them to solve a problem I had but passed on the idea. Maybe other members on here may remember or have experience with them.

Based on what I have experienced over the years, The members suggestions above are likely the direction to go.

If you try the Rails let us know how they work. It would be cool to see if you could correctly install them with a good waterproof 5200? bond/screw schedule to gain fuel efficiency, handling and speed.

I have a Question on your gas over there... Where does your boat gas come from? REPSOL, CEPSA? Are they blending blending Ethanol with it? Whats the Octane/RON?

[El Español]

Hehehe Nice picture #CUDA!

I sent it straight to my friend who owns a BatBoat I guess 22ft in Gibraltar.
His boat runs a 150HP V6 just at the transom + nosecones and Hyd jackplate. It takes around 60MPH.

but! If someone meet that boat on the rough, no way to catch it!!

Gibraltar it’s dangerous place for boats. It’s just a big Rock just on the peak of the very narrow meeting between the Mediterranean Sea and the Atlantic Ocean, it use to have terrible water conditions plus heavy traffic of cargos.

This Ocke Mannerfelt BatBoats they are designed to work trough the worst conditions! Instead of the cool “high fly attitude” brand of S&F or the classical offshore style “navigating” pair over pair of waves. The idea is going trough, called “Splash”.

If your duty is to go point A, to B, no matter whats on the middle, that’s your boat!

They are very very light hulls. Less than 700 pounds the 22ft. Everything is just on the middle of the longitudinal Axel. Two inline seats, battery, gas tank,,

As we can see in the picture, they are full of concave strakes + steps with special different angles. A piece of art with a different look 😎

[El Español]

Hi #ScottReierson!

Abbate was part of the golden era of Italian designers as Pininfarina, Bertone, Fabio Buzzi. These “Sea Star”, normally I/O, is his most recognisable model known as the “Ferrari of the seas”. As for other European designers, their boats become very expensive to be exported to USA. It’s why at your side of the pond is difficult to find an original Ocke Mannerfelt, Lorne Campbell or Steve Baker.

Now there is lot of treasures abandoned because there is not such culture of fast boats here than in USA.

About the gas, our petrol is GOLD PLATED! Around 7.50$ per gallon!!

Most common in order are: 1 Repsol, 2 BP, 3 Shell, 4 Cepsa
best Quality: 1 Shell, 2 Repsol, 3 BP/Cepsa
In the last years there some new “white brand” 5% cheaper but terrible quality.

For cars We have 95 and 98 octanes (lead free) + two variants called “plus” with some additive.
10 years ago Shell stops selling Super 97 octanes (with lead). That was the best of all!

At Puerto Banús we have only Repsol 95 octanes lead free “special marine”. Its quite a good gas, I have never seen water on filter separator with it.

Main issues you can find it with Diesel. For cars there is only available Diesel “Class A” or “Class A Plus” (+additives). When you serve Diesel on your vehicle, you find a code “B7” it means it has 7% of biodiesel. At some places you can find B10 or even B20.

No one pay attention to that, thus in cars is not a problem, because they have small tanks and refill them every short period of time.

But for boats it can be a big issue. The alive fungus contained in biodiesel can proliferate covering all tank and lines of a viscous materia. Past year a friend bought a yacht 50k underpriced because of that issue. He works with chemical stuff and fix spending 3 or 4k of his own stuff.

For boats at some “working marinas” you can find Diesel B, also for trucks. No experience with that.

[CUDA]

Have a wood shop cut you a beveled piece 8 or so foot long about 6 inches wide maybe 2 inch thick attach to the side of center keel so you'll end up with 2 or so inches from your existing V protruding, then have flatter pad area each side.

Be a lot easer with boat upside down.

[scott reierson]

Wow...Thanks for the answer on the fuel. Sounds like a lot wild choices. Amazing. I had no idea. Sorry to hear its that expensive.

In my area we have a lot of Ethanol mix. 87/10, 88/15 and E85. We are able to get 91-93 non Ethanol pretty easily. Higher Octane "race" gas is available if you know where to go. However it is sold at a much higher price. Diesel in my area is labeled "Low Sulpher" some of the Diesel is a Biodiesel Blend.

Thanks again for the reply back

[David]

Note that Europe uses RON and the US uses the average of MON and RON. Their numbers are not the same as ‘ours’

[HydroSkreamin]

Note that Europe uses RON and the US uses the average of MON and RON. Their numbers are not the same as ‘ours’

To add to David’s response, the European 95 RON is equivalent to US 89, and the European 98 RON is equivalent to US 91.