28 skater with twin bb-engines
 

just installed twin big-block (600hp-each) engines to a 28 skater.Confused about the rear-weight?!?. As I see noone uses twin inboard on a 28 boat . does anybody have any idea or comment about this combination?
:confused:

Pictures! I would think that it would be quite tail heavy. Why not small blocks or a single BB? Good luck on dialing it in as maybe only one other has been done.

Big Blocks in 28'
 

Timucin,
Why not check with Skater, I think that they have tried a lot of different combinations and as I always heard their boats work.
I have a 28 with twin big blocks, Just dont have enough money to have a Skater Hull.. Sound like you must have a good ride, sometime let us know how it performs, Handling that is, Know already that it will fly.:p :p :p

Regards, eliminator219:D :D :D

off course I asked skater first but I think they do not want anybody to touch/modify their boats.I am in Turkey so it is almost impossible for me to take the boat to skater just for rigging etc.

They told me to buy 32 :) which I am not interested for the moment.Cause we made side-by-side closed cockpit + installed the engines + did the first layer of paint +just received the props planning to test-drive in maximum ten days .Boat is almost finished .More then new boat marketing , just need some friendly advice.

I am still not sure about'' how will the boat will stay on the water with that much weight at the back of her when not runnin'?? where will be the water level at the back?? how the boat will react when I slow down fast?? etc..etc...

What drives are you using? Are the engines mounted all the way back on the transom? I think I would try to move the engines forward a little bit. Two big blocks in the back of a boat meant to have ouotboards is a lot of extra weight back there. I would think it will really want to get the bow in the air especially in the rough. Becarefull and slowly explore the handling charactaristics of your set up.

Tough to say for sure, but I've seen a lot of fast mid-size cats running a driveshaft. American Offshore, Spectre, even a Chris Cat with Bravos. Most were designed to run pretty flat and that much weight aft may not work well.
Gary

I'm certainly no cat or skater expert, but from a physics standpoint alone, I would be worried about some serious handling issues regarding longitudinal stability.

A pair of big blocks with bravos weighs about 1200# each, 2400# total which outweighs the 28 skater hull by 300#(2100# empty).

You may want to reconsider or question Douglas Marine further...

This is going to place the cg of the boat excessively aft(appr 25%-30% length from rear) and increasing the distance between the center of lift and the cg causing a positive pitch-up moment every time it leaves the water...

I would love to hear how the boat handles this after your test rides. I suspect you will have problems in the rough water. That is going to be a very tail heavy boat. I have to ask, why did you do this?

Post this in general discussion area and do a search there too on things like center of gravity, small boat with twins etc . There was a very helpful discussion there a while back on exactly what you are doing and all the "pros " jumped in to give some great advise .It was very good reading . Try it before you "fly it" !!:cool:

Install as many lightweight components on the engines as you can, exhaust,intakes,heads and so on. Install all other heavy items like batteries more foreward in the boat if possible. many of the 28's are rigged with 3 2.5 outboards at 400lbs each. this puts 1200 lbs at about 10 to 16 inches aft of the transom depending on jack plates etc... If you are installing 2 500efi w/bravo's for example they are 1113lbs each, that will put 2226lbs but the center of gravity for the engines should be about 14" to 22 inches foreward of the transom. If you could lighten the bb's by about 200lbs each then the delta would be only about 630lbs and the cg of the boat would be in the ballpark with the one with the triples----- a proven setup. Good luck and we all woulld like to see some photos The Ironman.

thnx for replies
 

thanks for all discussions
here are some answers to your questions

drives:bravo 1 drives powered by Imco 1.36:1 with low water pick-up lower units

engines bb (by weight point of view):carburated-aluminum intake man.-aluminum cylinder heads-light weight exhaust system with no water pump.

reason why I did this combination:was using the same boat with single 502 cu. :lost my interest ,my attention after some time,it became not exciting.
also some new boats with twin outboards (actually we never had a chance to try to with them)
I spend really lot of time by thinking about the twin outbord application but : the look and the sound of inboard looks really ''PRO'' and decide to do it.And I already had both of the engines.thats how its started. After installing the engines the back side of the boat became very high and we wanted to complete the look (and give a complete racy look)by making the side by side cockpit.

pictures:will collect them all untill monday but here are some photos

thanks for your ideas too much.please keep on sending

What where the specifications and performance numbers for the single motor?

x-engine was 502 cu.in 400-450hp

well Eliminator makes a 28ft daytona, I test drove one it had twin 496 chevys{8.1liter} it was a 2000 year model all stock, the boat was a dream to drive, it turned very well, and talk about move, that might be my next boat:D

H2Xmark!
thats the best thing I've heard for the last week(s!)

Hey good luck,my friend bought a 30 cobra with twins bbs and bravos,and the previous owner said 115,had extension boxes and said was a little lite in front when crankin,he took them off,but has yet to tryit happy boaaating, tripps

twin I/O's in a 28 cat
 

I have a 99 Advantage SPortcat with twin 502's
this boat is completly stock :(
There is alot of extra weight in the back.
One thing I would like to do and will do on the next boat is to have the engines mounted forward of the current setup.
They, Advantage have done several twin setups. They have done alot of these setups.
However, they are also a heavier Cat then Skater is.
They have not done any twin outboards on the 28 as of yet. :(
I would be real interested in how, if you did, you reset your stringers to handle the twins. I am glad to hear that at least the transom was setup for an i/o in the begginning. Isn't the transom thinner on outboard setups?

I do not sit level in the water. I have pictures of a single 28 sitting more level then mine.
Running can be a handle sometimes in the rough at slow speeds.
mine does not wake up until at 40 in rough lake wake.
anything under 40 requires the tunnel tab to keep the nose level.
I have been out of the water in mine a few times. Never ran offshore, but have never worried about mine blowing over.
Not sure if any of this will help. just my situation with a twin BB 28 cat

MNFASTBOAT!
can you pls send me a picture of your boat on the water?!?

I will try and post a couple here.
If this does not work click on my web page and i have several there. Should be a bouple in the water.
There is also a small movie down towards the bottom

another

this one is a ****ty one not that clear, but shows the level of the water line I beleive you are most interested in.
I think this one ahs been copied to many times :)

BB in a 28'
 

Timucin,
Take a look at Mnfastboats photos,Great looking ride!! What do you have to worry about? When you first posted I thought that you were going to hang a couple of big outboards on the back. I have no idea as to how it would sit, handle or anything else for that matter, but BB with alum. components, I wouldnt worryat all, Eliminator makes that setup and then hangs 12" boxes on to boot. Haven't heard of them blowing over. Let us know what you do...and good luck.:D :D :D
eliminator219

MNFASTBOAT
you have a very nice boat.finally I ve seen a same size boat pic. with twin BB's .thanx for pics.
I feel better now, cause only 4-5 days left to test-run
;)

Thanks guys for the compiments.
I really love the cat.

Sometimes I wish that I would have went with a BIG single.
But other times I love the twins. Like when docking :)

almost finished
 

she s almost finished will send pictures soon

Active Thunder's 32' cat is a skater hull. They are licensed to use the hull design. They put big blocks in their boats with out any problems. 500 EFI/ Bravo packages in standard configuration. They have a web site, or call them, they are near Ft. Lauderdale Florida.

is it same in states that mechanics never keep their promises?
 

waiting mechanics , to test the boat .everything is ready even the gas.after 2 years + 2 much cash +xxxx hours of brainstorm. everything is ready but the mechanics........