Enlistments, Evaluations, and Advancements, COMDTINST M1000.2 (series) provides​ the policies for Sea/Surf Duty for Advancement and Sea/Surf Duty and Award Points for Servicewide Exam Competition. Note that the policies are discussed in two separate articles. 

1. Article 3.A.16 covers Sea/Surf Duty for Advancement. 
2. Article 3.A.17 covers Sea/Surf Duty and Award Points for the SWE Competition. 

This should help drive home the fact that these are two different topics.

The sea/surf duty time for advancement and points are both calculated​ based on Direct-Access data entry (e.g., PCS report / depart dates, Surfman competencies, and Career Sea Pay start / stop dates). However, different rules apply as to when the "clock stops" with regard to periods of TDY away from the CSP eligible vessel. 

Let's take, for example, a member who is sent TDY to their cutter's home port while the cutter is in the shipyard (located beyond a reasonable commuting distance from the home port) for an extended refit or service life extension. 

Their entitlement to Career Sea Pay/Time will stop after the 30th day away from the cutter (provided they're not TDY to another CSP eligible vessel) - The sea pay/time "clock stops" in Direct-Access.

The member's Personal Data Extract (PDE) for an upcoming SWE may show them as "Not Eligible" because of the Direct-Access sea pay/time clock. The Eligibility Results field will read "AS of MM/DD/YYYY you are not qualified for advancement due to the following reason(s): -- SEADUTY - Member does not have enough Sea Time for Eligibility." 

If the member is qualified for advancement in all other respects, they may be authorized a "waiver" of the sea duty for advancement requirement. I put the word waiver in quotes because the SWE waiver process must be used to tell PPC (ADV) that the member is qualified (the SWE waiver process is outlined in the Servicewide Examination Guide). We're not really waiving the requirement it is just that the computations for sea duty points and sea duty time for advancement are coupled together. However, if the member would have met the sea duty requirement for advancement had they not been sent TDY back to the home port while the cutter was in the shipyard, they are eligible to participate in the SWE.

They are not eligible for points based on the time the CSP was stopped. Remember - Two different topics.

For a member in this scenario, entire period of assignment to a CSP eligible cutter is creditable towards the eligibility for 

• Temporary, Permanent, or Master Cutterman, 
• Gold and Silver Ancient Mariner, and 
• advancement for ratings that have sea duty requirements.​ 

Also you should note that although the period spent away from the cutter while it is in an extended yard period is not a period for which CSP is payable or career sea time accrues, the period is neutral time for accruing sea time required for CSP-Premium ($100/mo. payable after completion of 36 consecutive months' sea duty in addition to the CSP payable for sea duty assignments).​

Also see:

ALCOAST 455/16 CSP During Extended Shipyard Periods

Flag Voice 466 EXTENDED SHIPYARD CAREER SEA PAY (CSP) POLICY CLARIFICATION

Comdt (CG-1222) Memo 7220 dtd 21 Sep 16/ Memo CSP and Responsibility Pay Entitlement During 225' WLB MMA Periods

Comdt (CG-133) Email dtd 13 Jan 17 (Sea Pay clarification of policy; enlisted member's will be still be credited sea time for SWE eligibility, cutterman, etc purposes, but will NOT accumulate Sea Time Points for SWE purposes) (CG Portal Link - CAC Logon Required)