Howdy Bryan214. I believe you have a 1971 Bulova "Sea King" as shown in this 1972 ad posted by Bobbee. I'm not knowledgeable about taking the back off of one of these. I've never had one. It may be a front loader movement. Hopefully someone here will know.

It does look like the Sea King. Great to have your Grandfathers watch. It's the same thing that started most of us down this collecting path!
The 'T' is for Tritium lume on the hands and dial. I agree with Sea King, and it may very well be a front loading case. I recommend taking it to watchmaker to know for sure, and I always recommend getting a full CTR service if you plan to run it regularly. Nice condition.
The Lug ends on the "SEA KING" in the ad appear to be straight across, while the lug ends on the subject watch seem to slant??
In reply to The Lug ends on the "SEA by timerestoration
I'm seeing that slight case/lug slant difference too. There are many similar case shapes, even just in the ad above. If you let the watch run down, then wear it for a bit and it "winds", we can determine if its an automatic.
Sea King. The watch is what we call a front loader and you will need to take it to a trained watch repairman. The stem will pull out all the way if pressure is applied and the movement will be free. You will need to remove the crystal and bezel and the movement will then be able to drop out through the front, this is a trickey job and not recommended for the non-trained person. Good luck and thanks for sharing your family heirloom with us.
Hi Bryan, welcome to myBulova. First of all, you have a priceless heirloom. Not because it's an old or even rare Bulova but because it's your Grandfather old Bulova, you are most fortunate.
I will go along with my peers in voting it a Sea King. Jeff (timerestoration) and Will have an excellent point regarding the lug curve but I'm seeing a slight curve in the advert ( ever so slight I should say though). In our movement dB we show a 11AC movement that is a manual wound 17 jewel movement. Pretty basic but a good workhorse I'd say. Agreeing with the Reverend, service it regularly and wear it proudly, it's a fine watch and a proud family history!
If you need a recommendation for a good, professional watchmaker to service it, just ask, we have several just on this page alone!
yeah I'm good with Sea King
I would also agree with Sea King
Sea King even for me