This article is a first draft summary of the Shulchan Aruch Harav and is pending further review of additional sources.

Having separation between one’s heart and Erva during learning and Davening:[1]

The Sages added that not only is it forbidden for one’s eyes to see the Erva during prayer or learning Torah, but it is even forbidden for one’s heart to the Erva during prayer or learning Torah. Meaning, that if there is no separation between the heart and one’s Erva, then it is forbidden to say Shema or learn Torah. Thus, if one is naked under his blanket he may not say Shema or learn Torah until he makes a separation. The other limbs of the body, however, may see the erva, as only the heart and eyes were prohibited.

The following is considered a valid form of separation:

• Place a hand over the blanket below one’s heart.
• Wear pants[2]
• Wear a belt[3]
• Embrace one’s body under the sheet.

While in water:[4] If one is naked inside water [such as a swimming pool, or river, or ocean] then if then if one’s heart is above the water, the water acts as a separation and one may learn Torah and say blessings. If one’s heart within the water, then if the water is clear, one is required to cover his heart with a cloth. Using one’s hand to cover himself is not valid. However, if one embraces himself with both arms, then it is a valid separation. If the water is dirty, then it is permitted to learn Torah and say blessings even if one’s heart is in water. However, if the water smells putrid [or one is in an unclean area] then it ios forbidden to learn or Daven.  

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[1] Admur 74:1; Ketzos Hashulchan 9:2

[2] Ketzos 9:2

[3] Ketzos 9:2

[4] Admur 74:3