Making a block around detail.

Hi!

I have a problem with a piece that i want to make a presstool around. And i have tried with everything i can possible think of.

-'Extrude to surface dosen't work, if i offset surface i do not come any further with that either.

- I looked on youtube to find some tutorial for help but nothing so far.

My question is:

Can you possible make som kind of archimedes principle in Solidworks? You know lower a part into a block and "cut" away the form of the piece in the block?

Like to lower a boat into water.

Excuse my bad english i hope you can understand my problem.

Thankful for help ASAP.

SolidworksParts And Features