Staggering + building a 20" notch?
 

Will a 20" notch be asking for trouble on a 90's 38' Scarab Thunder with standard Bravo 1's?

I have a 38' Scarab Thunder on which I will rebuild the transom and engine room stringers next year. Looking down at the engines I realize that there's so much room in front of the Engines that if I extend the engine compartment by making a 20" notch (and move the transom back 20") it will be possible to mount the engines in a staggered configuration rather than side by side (the way it looks today). There are a number of reasons this could be a great advantage:

+ Most of the advantages of staggered engines (More room to work on the engines, Drives closer to the center = better propeller grip with lower mounting height, More weight moved closer to the centerline, etc)
+ A 20" notch enabling the x-dimension to be raised, although the drives will be deeper down towards the V (higher top speed)
+ Better angle of attack for the drives to work with (easier to trim the boat, easier to get on plane, and a higher top speed)
+ Still the same cockpit space, as I will only use the existing space in front of the engines
+ No shifting of the COG, as the extension would be in the shape of a notch

There are also a number of negatives of course:

- More work
- Less maneuverability when docking
- The possible risk of unpredicted negatives in handling, as this has not been done previously...

What do you think? Should I do it, or should I stick to just rebuilding everything the way it looks, and follow the old saying "If it ain't broken, don't fix it"...?

The biggest benefits in my world would be accessibility. Extension boxes and short lowers cost to much (due to import taxes and a poor dollar exchange rate where I live), and would not cure the access issue of side by sides. Glassing is relatively cheap and I can do it myself, although staggering requires a lot of complimentary stuff like extended driveshafts, etc...

Any inputs will be appreciated!

I like a guy who is willing to innovate and try things no one has done before. If you think you have a good plan, I say go for it.

What kind of exhaust do you have??

My exhaust? This should be the least problem, but since you are asking:
I have stock 496 engines with stock manifolds and risers. Behind these there are 4" rubber hoses (as in most boats of this kind), and then a couple of custom made H-pipes with downturns and a special type of external choice that I made myself. Works well, and is really effective. The best part is that I can chose from silent mode or noisy mode when cruising at high speed without having the exhaust pass through some pipe the size of a milkshake straw, thus (hopefully) extending the life of the valvetrain and head gaskets... :)

Rebuilding to staggered would present a new challenge in building a new type of external silent choice exhaust, which could be really interesting!

The big question in my mind however is whether 20" of transom notch would work or if it's way too much on a non-stepped Scarab 38 with stock Bravo drives...?

How do you intend to do the notch? Usually the notch is cut into the transom, sounds like you are trying to leave the "notch" at its current location, and planning on moving the transom back. That is a big endeavor, as you would need to extend the top deck, and the sides as well.


http://www.offshoreonly.com/forums/c...flat-deck.html

YOU need to work with someone who has experience in this type of work...first, you don't move the transom back, and LOWER mounting height? I say you are opening a can of worms if you don't have experience with this stuff. And i believe there are a few 38' Scarab's with Staggered engine configurations.
hmmmmmm, good luck?!?

correct, I have seen several factory staggered early eighties 377's (essentially a raised flat deck 38 but the same hull as all straight bottom 38 Scarabs. Never seen anything newer then about an 82 though.


http://www.offshoreonly.com/forums/s...38-scarab.html

I have played with this idea many many times when I started looking for a 38 Excel, ended up getting a 38 Thunder and still tossed it around but ultimately I dont want to give up cockpit space required to do it. I even entertained the thought of just lengthening the boat at the transom, which is do-able but extremly advanced. I would still love to do it but to much to give up.

All your thoughts sound good to me. If you don mind the work, go for it.

Yes, that's exactly what I had in mind, and yes - that is a big endeavor...

I have some experience in this type of work, and you are right - I shouldn't be done otherwise. Moving the engines closer to the centerline of the hull requires lowering them if you don't want to end up having raised your x-dimension about 10" which is far too much, as the drives would end up closer to the center of the V in a staggered configuration. However, since the drives are mounted quite low from factory on these boats you don't need to lower the engines that much. Also, creating a notch would allow for an even higher mounting height compared to a full straight bottom, counting from the bottom and up (as one should count the x-dimension), allowing for yet another "raise" of a couple of inches or some more depending on the length of the notch.

Yes, the old 377 Scarabs... I used to own one myself. It was a nice boat but it weighed more than 50% more than my 38 Thunder!!! On the very same sublift (with a good accuracy) the 377 weighed in at 5995 kg, compared to the 38 Thunder's 3970 kg! The Thunder also feels like it is more solid in terms of less twisting and turning in the hull... The old 377 was a mechanics dream, having oceans of engine room space, but as long as there is no need for changing a starter or something like that, I like the Thunder better. The thing is that I'd want to have both staggered engines AND my 38 Thunder... I know there were a few 38 flatdecks built for racing purposes with staggered engines. When all comes down to it, I guess I might find myself reasoning like you do, Glassdave; "Too much to give up..."
:)