Their dad had owned “Bonnie Belle”, a Catalina 27-foot sailboat, for so many years that Marci, the seventeen-year-old daughter, claimed that Jeb, her fifteen-year-old brother, was probably conceived in the vee-berth. Their mom, the Bonnie that the boat was named for, did not dispute that.

When Marcie would sleep with her brother in that vee-berth she would sometimes hear her parents getting it on as quietly as they could at the other end of the boat which is, of course, not far away. Her fingers would creep between her legs as soon as she understood what they were doing.

One very memorable summer week, when their parents were going away, they got permission to stay on the boat. Both were competent sailors by now and the idea of setting their own course was thrilling.

Their first evening there, still at the marina, it got even more thrilling. Marcie complained about the heat so crawled into the vee-berth naked. She’d expected Jeb to take the stern one but they’d slept together so many times he just joined her, wearing only some loose shorts. It was a moonlit night and plenty of that illumination came through the ports.

Marcie was dozing off and she noticed a rhythmic shaking of the bed. Since she was lying on her side facing her brother she opened her eyes to see him staring at her with his hand inside his shorts and moving. He was rubbing one out!

Without warning, she reached over and put her hand on his cock, saying softly “I can help that and it’ll be more fun for you.” After he got over the shock, he pushed his shorts down and watched his sister making him feel pretty damn good.

She had enough experience to tell when he was about to shoot so she quickly bent over and took the head in her mouth and discovered he tasted pretty good. After swallowing she commented, “A lot less messy that way.” She moved back to her side of the bed, closed her eyes and went to sleep leaving a stunned brother to absorb all that had just happened.

In the morning she was up making coffee and fixing breakfast, still in the nude and said hi to him just like it was any other morning. He put his shorts back on but she saw them tent. Laughingly she said, “It’s not going to be easy for you to piss like that. Want me to make it soft again?”

He nodded so she knelt down and gave him a real blow job this time. Then he was ready to walk to the bathroom. When he came back they sat down to eat. Jeb was full of questions after those experiences. “Marcie, when did you learn to do that?” There was no doubt what he was referring to and she grinned, “Oh about two years ago. I’ve learned a bunch of other stuff too. Since I’m your big sister I guess if you have questions you can ask me.”

That statement opened the door. Jeb’s next question was, “I know you’ve had a bunch of boyfriends since you turned 16. Do you fuck them?”

Marcie kept grinning, “Only if I like them. Some guys were too arrogant or felt entitled to my pussy so they didn’t get any. Some of the other girls like bad boys but not me. Let’s turn this around for a moment. Have you ever fucked?”

Jeb shook his head and said he’d never had a blowjob before either. As a matter fact hers was the first naked female body he’d ever seen live, although there were plenty on the Internet.

“Well you can’t touch those or have very much fun with them. How about we use mine to teach you some things? We’ll do that later but I want to get out sailing now.” They cleaned up the galley and got the rigging ready to go. Jeb started the engine and they backed out of their slip and headed out through the breakwater. This was a big lake but not overly developed so there were many coves to anchor in and have them all to yourself. They had some favorites from their years out here with their parents.

Three pleasant hours later they were furling the sails and setting the hook (anchor) in a small tree-lined cove which would give a great view of the sunset. Marcie stripped and dove in while Jeb put down the swim ladder and followed her in. The water was pleasantly cool.

When they climbed out Marcie went first and Jeb got a closeup view of her lightly furred pussy and her puckered hole framed by tight buns. His male reaction occurred even in the cool water and was wagging when he came into the cockpit. Marcie smiled as she handed him a towel, “Looks like your guy part wants some more attention.”

She pulled a cushion to the cockpit floor and laid him on it, then positioned herself over his waist. He wondered, “Is she going to fuck me?” Her pussy got lower and lower, finally resting on his hard shaft, pinning it to his belly. Her hips began sliding that slippery slit to and fro along the tingling tool and she made humming sounds of pleasure. It was too much to resist, even if he’d want to, and he soon added his own pleasure groans as whitish cream spurted several times out of his dick head and splattered all the way up to his neck. Marcie reached her fingers for it and rubbed the wetted ones on her clit until she shook in her own peak.

“Now that we’ve eased our tensions,” Marcie said lightly, “we could do a bit of education.” She sat up on the cockpit seat and splayed her legs. “Move closer so you can see the details.” She pointed out the parts of her crotch, using both medical and slang terms. She was very academic, especially with what had just happened. Jeb had not completely deflated, she noticed. Good. “Go ahead and touch me. I’ll enjoy that. You can use your tongue, as I’m sure you have seen online. I like that a lot.”

Jeb was guided to give her another orgasm and she gave him a handjob that sprayed her vaginal entrance with his copious cream. She was HOT and it took all her resistance to keep from pulling him in deep.

Just before sunset a very small sailboat anchored a few hundred feet away. It appeared to have one male crew. They waved then turned to enjoy the sunset. Marcie was wearing only a t-shirt as she sat in with her back against his chest. He put his arms around her and they soaked up the beauty of nature.

A board game was fun and then it was bedtime. Off came the shirt and she snuggled close to her brother. The close contact triggered the usual biological reactions and Jeb wondered how they would be eased this time. He decided to begin a conversation since he had many unanswered questions. “What started you having sex?”

She chuckled, “A smart guy with a horny dick. He charmed my pants off after pushing all my physical and emotional buttons and I was hooked. I’m amazed I didn’t get preggers before Mom figured it out and got me on contraception. When he moved on I found another. It was awfully easy just like with you. There was one more after him until I met Josh. I was fucking both of them for a while and loved it but the other guy couldn’t compete. Anything else you want to know?”