You probably already know that Heliax is generally referred to as "hard line" because it is not flexible and therefore difficult to route through conduit or any obstruction. An additional reason not to use it is there is little benefit in terms of loss or longevity. While it has slightly lower loss at VHF than LMR, the difference is trivial especially for short runs typical of any boat.
My suggestion is to save yourself the extra expense and aggravation of Heliax and use the LMR coax. Depending on the run, the 200 version may be acceptable -you can easily research the loss characteristics to determine.
