如买方未能按造船合同支付节点款，在合同项下违约，卖方根据合同需要向买方发出违约通知，如下：

To [The Buyer],

Reference is made to the Shipbuilding Contract dated [date of contract] (hereinafter called the “CONTRACT") made by and between [the Buyer] (hereinafter called the "BUYER") on one part and [the Seller] (hereinafter collectively called the “SELLER") on the other part. The CONTRACT is relating to one (1) [Vessel], bearing [the Builder] Hull No. [Hull No.] (hereinafter called the “VESSEL").
Clause 3(c) of Article II of the CONTRACT expressly provides that, “The sum of United States Dollars [amount] (US$ [amount]), representing ten percent (10%) of the Contract Price, shall become due and payable and be paid within three (3) Business Days after keel laying of the first section of the VESSEL.. ...”.

The keel laying of the VESSEL has taken place on [date of keel laying]. We sent the demand for payment together with the Confirmation of [classification] (via [Broker]) to you on the same day. Furthermore, in consideration of long term cooperation and relationship between parties, we granted your request for an extension of this payment for 20 banking days, i.e. the third instalment shall be paid by the BUYER latest on [deadline of payment]. However, we have not received the payment until now.

Under such circumstances, the BUYER shall be deemed in default of its obligation under the CONTRACT in accordance with Article XI. The SELLER hereby gives this notice and reserves all our rights under the CONTRACT. We hereby demand once again that you shall pay the third instalment under the CONTRACT as soon as possible.

For the sake of good order, please acknowledge your receipt of this letter by return.

Yours faithfully

[the Seller]