Keel joint arrangements for floating platforms

In a floating platform having a hull with a keel, and a riser opening having a lower end at the keel and extending upward through the hull, the improvement comprising:

• a landing profile in the riser opening adjacent to the lower end of the riser opening;
• a guide sleeve having an engagement profile that lands and locks on the landing profile for movement with the hull;
• a collar being located within the guide sleeve and having
• a flex member extending into the guide sleeve adjacent to the lower end of the riser opening, the flex member retaining the collar with the guide sleeve, but allowing angular movement of the guide sleeve relative to the collar due to movement of the hull, the flex member having an upper end spaced below an upper end of the riser opening;
• and
• a riser extending slidingly through the collar and the riser opening.

A method of preventing contact of a riser with a lower end of a riser opening extending upward through a hull from a keel of a hull, comprising:

• providing a landing profile in the riser opening adjacent to the lower end of the riser opening;
• assembling a flex member within a guide sleeve;
• extending a riser through a passage in the flex member;
• lowering the riser through the riser opening along with the flex member and the guide sleeve;
• then
• landing and locking the guide sleeve on the landing profile with the flex member adjacent to the lower end of the riser opening;
• then
• continuing to lower the riser while the flex member and the guide sleeve remain in the riser opening and securing a lower end of the riser to a subsea location;
• then
• as waves cause movement of the hull relative to the riser, allowing the hull to move relative to the riser with the flex member allowing angular movement of the guide sleeve relative to the riser.