How do I get signalk data into node red

[e-sailing]

My question now is is it also possible to write to the Signal-K on openplotter ? 
I see that there are several Input UDP ports defined in openplotter. But not specifically for node Red.
Somebody knows this and has an example ?

Yes. There is no special port for this. For notifications you should use 55558. For other sensor use 55559.
Here is an example to send RPI cpu temperature to SignalK as 'environment.inside.heating.temperature'

Code:

[{
        "id": "f5fa759f.be894",
        "type": "inject",
        "z": "4deb498f.fbcfd8",
        "name": "",
        "topic": "",
        "payload": "",
        "payloadType": "date",
        "repeat": "5",
        "crontab": "",
        "once": true,
        "x": 134,
        "y": 120,
        "wires": [["adb4b4a8.9c10c8"]]
    }, {
        "id": "adb4b4a8.9c10c8",
        "type": "exec",
        "z": "4deb498f.fbcfd8",
        "command": "vcgencmd",
        "addpay": false,
        "append": "measure_temp",
        "useSpawn": "",
        "timer": "",
        "name": "getCPUtemp",
        "x": 323,
        "y": 161.5,
        "wires": [["2705f134.792f86"], [], []]
    }, {
        "id": "7b5088a.c5f0af8",
        "type": "debug",
        "z": "4deb498f.fbcfd8",
        "name": "",
        "active": false,
        "console": "false",
        "complete": "payload",
        "x": 740,
        "y": 147.5,
        "wires": []
    }, {
        "id": "2705f134.792f86",
        "type": "function",
        "z": "4deb498f.fbcfd8",
        "name": "msg.payload",
        "func": "cpu_temp = parseFloat(msg.payload.replace(\"temp=\",\"\").replace(\"'C\\n\",\"\"));\ncpu_temp = cpu_temp + 273.15\nmsg.payload = '{\\\"updates\\\": [{\\\"source\\\": {\\\"type\\\": \\\"ARMTEMP\\\",\\\"src\\\" : \\\"RPIMCU\\\"},\\\"values\\\":[{\\\"path\\\": \\\"environment.inside.heating.temperature\\\",\\\"value\\\":'+cpu_temp+'}]}]}\\n';\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "x": 533,
        "y": 210,
        "wires": [["7b5088a.c5f0af8", "c17f4c75.737088"]]
    }, {
        "id": "c17f4c75.737088",
        "type": "udp out",
        "z": "4deb498f.fbcfd8",
        "name": "sendSK",
        "addr": "localhost",
        "iface": "",
        "port": "55559",
        "ipv": "udp4",
        "outport": "",
        "base64": false,
        "multicast": "false",
        "x": 742,
        "y": 221,
        "wires": []
    }
]